EDIT:

This is your problem:

for element in data:
    if '2-uID' in element:
        del element['2-uID']

data is the top-level element, so it only has one key: "uID". Try printing out "element" :)

Maybe I'm misundertanding you, but shouldn't you just use del ?

This works for me

# string holding the JSON object
s = r"""{
    "uID": {
        "1-uID": {
            "username": "1-username",
            "pinned": true
        },
        "2-uID": {
            "username": "2-username",
            "pinned": false
        },
        "3-uID": {
            "username": "3-username",
            "pinned": false
        }
    }
}"""

import json

j = json.loads(s)

# remove one of the elements
del j["uID"]["2-uID"]

# see that the element is now gone
print(j)

# output:
# {'uID': {'2-uID': {'pinned': False, 'username': '2-username'},
#          '3-uID': {'pinned': False, 'username': '3-username'}}}

You will have to read the file, convert it to python native data type (e.g. dictionary), then delete the element and save the file. In your case something like this could work:

import json

filepath = 'data.json'
with open(filepath, 'r') as fp:
    data = json.load(fp)
del data['names'][1]

with open(filepath, 'w') as fp:
    json.dump(data, fp)

Here's a complete example that loads the JSON file, removes the target object, and then outputs the updated JSON object to file.

#!/usr/bin/python                                                               

# Load the JSON module and use it to load your JSON file.                       
# I'm assuming that the JSON file contains a list of objects.                   
import json
obj  = json.load(open("file.json"))

# Iterate through the objects in the JSON and pop (remove)                      
# the obj once we find it.                                                      
for i in xrange(len(obj)):
    if obj[i]["ename"] == "mark":
        obj.pop(i)
        break

# Output the updated file with pretty JSON                                      
open("updated-file.json", "w").write(
    json.dumps(obj, sort_keys=True, indent=4, separators=(',', ': '))
)

The main point is that we find the object by iterating through the objects in the loaded list, and then pop the object off the list once we find it. If you need to remove more than one object in the list, then you should store the indices of the objects you want to remove, and then remove them all at once after you've reached the end of the for loop (you don't want to modify the list while you iterate through it).

It’s pretty easy to load a JSON object in Python. Python has a built-in package called json, which can be used to work with JSON data. It’s done by using the json module, which provides us with a lot of methods which among loads() and load() methods are gonna help us to read the JSON file.

Deserialization of JSON

The Deserialization of JSON means the conversion of JSON objects into their respective Python objects. The load()/loads() method is used for it. If you have used JSON data from another program or obtained as a string format of JSON, then it can easily be deserialized with load()/loads(), which is usually used to load from string, otherwise the root object is in list or dict.

json.load(): json.load() accepts file object, parses the JSON data, populates a Python dictionary with the data and returns it back to you.

Syntax:

json.loads(file object)

Normal reading from json would be -

# Python program to read 
# json file 


import json 

# Opening JSON file 
f = open('data.json',) 

# returns JSON object as  
# a dictionary 
data = json.load(f) 

# saving the records array
records = data["records"]

# Iterating through the json 
# list from records array
for i in data['records']: 
    print(i) 

# Closing file 
f.close() 

Now according to your use case, you just need the records and no other keys from json. rather than removing it from json, you can just access it with data["records"] that would solve the issue.

However, if you still want to remove it then you can use data["records"] from json and store it in a variable. You will then have to write that into the file for persistence.

 for element in values:     
     if 'data' in element:     
         del element['data']     
         print("check")     
     if 'BriefInfo' in element:     
         del element['BriefInfo']     
     if 'UserName' in element:     
         print("SSS")     
         del element['UserName']     

elif needs to be if. on each iteration data is found first so it falls into that if statement and skips the others.

Try this:

weapons = list(weapons_dict["weapons"])
for i, weapon in enumerate(weapons):
    if (weapon['game']=="DELETE" and weapon['weapon']=="DELETE" and weapon['down']=="0" and weapon['up']=="0" and weapon['left']=="0" and weapon['right']=="0"):
        del weapons_dict["weapons"][i]

That iterate over the list using i as the current index and then it will call del weapons_dict["weapons"][i] when ever it needs to delete that weapon.

It looks like the data in 'firetobq_peripheral.json' is not valid json. If each row is on a new line you can use this code:

with open('firetobq_peripheral.json', 'r') as in_file:
    dicts = []
    for line in in_file.readlines() : 
        d = json.loads(line.strip())
        if d.get('Peripherals'): 
            del d['Peripherals']
        dicts += [d]

with open('firetobq_peripheral.json', 'w') as out_file:
    out_file.write('[\n')
    for i,v in enumerate(dicts):
        out_file.write(json.dumps(v)+('\n' if i == len(dicts)-1 else ',\n'))
    out_file.write(']')

with open('firetobq_peripheral.json', 'r') as in_file:
    dicts = json.load(in_file)
    for d in dicts: 
        if d.get('Peripherals'): 
            del d['Peripherals']

with open('firetobq_peripheral.json', 'w') as out_file:
    out_file.write(json.dumps(dicts, indent=2))

You can just open and close the file in 'w' mode:

open('Screentime/activities.json', 'w').close()

This is going to remove completely any content from your file. In other words, your file will be empty.

EDIT: While this answer does provide the result the OP asked for, it should be noted that an empty file is not a valid JSON file. More details can be found here.

Let's assume you want to overwrite the same file:

import json

with open('data.json', 'r') as data_file:
    data = json.load(data_file)

for element in data:
    element.pop('hours', None)

with open('data.json', 'w') as data_file:
    data = json.dump(data, data_file)

dict.pop(<key>, not_found=None) is probably what you where looking for, if I understood your requirements. Because it will remove the hours key if present and will not fail if not present.

However I am not sure I understand why it makes a difference to you whether the hours key contains some days or not, because you just want to get rid of the whole key / value pair, right?

Now, if you really want to use del instead of pop, here is how you could make your code work:

import json

with open('data.json') as data_file:
    data = json.load(data_file)

for element in data:
    if 'hours' in element:
        del element['hours']

with open('data.json', 'w') as data_file:
    data = json.dump(data, data_file)

EDIT So, as you can see, I added the code to write the data back to the file. If you want to write it to another file, just change the filename in the second open statement.

I had to change the indentation, as you might have noticed, so that the file has been closed during the data cleanup phase and can be overwritten at the end.

with is what is called a context manager, whatever it provides (here the data_file file descriptor) is available ONLY within that context. It means that as soon as the indentation of the with block ends, the file gets closed and the context ends, along with the file descriptor which becomes invalid / obsolete.

Without doing this, you wouldn't be able to open the file in write mode and get a new file descriptor to write into.

I hope it's clear enough...

SECOND EDIT

This time, it seems clear that you need to do this:

with open('dest_file.json', 'w') as dest_file:
    with open('source_file.json', 'r') as source_file:
        for line in source_file:
            element = json.loads(line.strip())
            if 'hours' in element:
                del element['hours']
            dest_file.write(json.dumps(element))

First question

However, whenever there's more than two elements and I enter anything higher than two, it doesn't delete anything. Even worse, when I enter the number one, it deletes everything but the zero index(whenever the array has more than two elements in it).

Inside delete_data() you have two lines reading i = + 1, which just assignes +1 (i.e., 1) to i. Thus, you're never increasing your index. You probably meant to write either i = i+1 or i += 1.

def delete_data():    # Deletes an element from the array
    view_data()
    new_data = []
    with open(filename, "r") as f:
        data = json.load(f)
        data_length = len(data) - 1
    print("Which index number would you like to delete?")
    delete_option = input(f"Select a number 0-{data_length}: ")
    i = 0
    for entry in data:
        if i == int(delete_option):
            i += 1  # <-- here
        else:
            new_data.append(entry)
            i += 1  # <-- and here

    with open(filename, "w") as f:
        json.dump(new_data, f, indent=4)

Second question: further improvements

Is there a better way to implement that in my Python script?

First, you can get rid of manually increasing i by using the builtin enumerate generator. Second, you could make your functions reusable by giving them parameters - where does the filename in your code example come from?

# view_data() should probably receive `filename` as a parameter
def view_data(filename: str):   # Prints JSON Array to screen
    with open(filename, "r") as f:
        data = json.load(f)
        # iterate over i and data simultaneously
        # alternatively, you could just remove i
        for i, item in enumerate(data):
            name = item["name"]
            chromebook = item["chromebook"]
            check_out = item["time&date"]
            print(f"Index Number: {i}")
            print(f"Name : {name}")
            print(f"Chromebook : {chromebook}")
            print(f"Time Of Checkout: {check_out} ")
            print("\n\n")
            # not needed anymore: i = i + 1

# view_data() should probably receive `filename` as a parameter
def delete_data(filename: str):    # Deletes an element from the array
    view_data()
    new_data = []
    with open(filename, "r") as f:
        data = json.load(f)
        data_length = len(data) - 1
    print("Which index number would you like to delete?")
    delete_option = input(f"Select a number 0-{data_length}: ")
    # iterate over i and data simultaneously
    for i, entry in enumerate(data):
        if i != int(delete_option):
            new_data.append(entry)

    with open(filename, "w") as f:
        json.dump(new_data, f, indent=4)

Furthermore, you could replace that for-loop by a list comprehension, which some may deem more "pythonic":

new_data = [entry for i, entry in enumerate(data) if i != int(delete_option)]