None of the items in your list are integers. They are strings which contain only digits. So you can use the isdigit string method to filter out these items.

items = ['1','introduction','to','molecular','8','the','learning','module','5']

new_items = [item for item in items if not item.isdigit()]

print new_items

Link to documentation: http://docs.python.org/library/stdtypes.html#str.isdigit

You can use this if you want to remove numbers less than 10 from the list and Calculate the sum of the remaining numbers

n = int(input("Enter number of elements : "))
a = list(map(int, input("\nEnter the numbers : ").strip().split()))

if len(a) == n:
    for num in a:
        if num < 9:
            a.remove(num)
    print('sum',sum(a))
else:
    print(f"You must enter {n} number") 

I find using isalpha() the most elegant, but it will also remove items that contain other non-alphabetic characters:

Return true if all characters in the string are alphabetic and there is at least one character, false otherwise. Alphabetic characters are those characters defined in the Unicode character database as “Letter”

my_list = [item for item in my_list if item.isalpha()]

It would be much better if you could tell what all kind of values are kept in number_values like date/time (in other formats), currency (other formats like 500 won), etc which you may or may not want to keep.

I can see that you want to keep first a date format and a string, and exclude everything else, which can be done be like this:

number_list = ["December 31, 2020", "10.00%", "$50", "1,452", "7", "testing", "(1)", "(1000)"]
new_list = []
garbage_list = []
for i in number_list:
// only check for first or second character for digits
   if i[0].isdigit() or i[1].isdigit(): 
      garbage_list.append(i)
   else:
       new_list.append(i)
print(new_list)

Output:

['December 31, 2020', 'testing']

More information would require a robust solution.