Try this:

function delete_row(&$array, $offset) {
    return array_splice($array, $offset, 1);
}

function delete_col(&$array, $offset) {
    return array_walk($array, function (&offset) {
        array_splice(offset, 1);
    });
}

Tested on Ideone: http://ideone.com/G5zRi0

Edit (Amade):

delete_col function can also be slightly modified to work with arrays with missing columns:

function delete_col(&$array, $key) {
    return array_walk($array, function (&key) {
        unset(key]);
    });
}

This can be used e.g. when you need to iterate over an array and remove some columns in each step. A function using array_splice instead of unset would not be appropriate in such scenarios (it's offset-based and not key-based).

First when you do unset ($row[count($row)-2]); you are are just unsetting an index of the $row variable which is just a copy of the value from your array. So you are not deleting the value in the array. Secondly, when you do $row[count($row)-2] you are assuming your $row has numerical indexes, which is not the case here. You want to delete the item_name index so you have to do something like unset($array[$index]['item_name']).

for(length = count($array); length; ++$i)
{
    unset($array[$i]['item_name']);
}

You can try something like this:

$array = [
   [
    "picture_id" => "0",
    "car_name" => "CA",
    "from" => "2018",
    "to" => "2020"
  ],
       [
    "picture_id" => "1",
    "car_name" => "WA",
    "from" => "2010",
    "to" => "2019"
  ]
];

    $whitelist = array("from", "to");
    $finalArray = [];
    foreach ($array as record) {
        foreach ($record as item) {
            if (!in_array(whitelist)) {
                $finalArray[key] = $item;
            }
        }
    }
print("<pre>".print_r($finalArray,true)."</pre>");

What will print out:

Array
(
    [0] => Array
        (
            [picture_id] => 0
            [car_name] => CA
        )

    [1] => Array
        (
            [picture_id] => 1
            [car_name] => WA
        )

)

A short explanation...Basically you are looping over multi dimensional array as

foreach($array as value)

Where value is "inner" array, so in order to remove some elements from inner, and create a new multi dimensionalarray, you have to use keys, like in my example, from original array. So you than actually make an array like:

$newArray[innerArray

And this gives you multi dimensional array. BR

const MAX = 2; // maximum number of elements
foreach ($array as &$element) {
    $element = array_slice($element, 0, MAX);
}

foreach ($_SESSION["addedToCart"] as &$arr)

& turns your variable into a reference instead of a copy. Normally this would be sufficient. unset() only works on data within the current scope (so your foreach loop) leaving the original unchanged (See unset() for details).

Instead you can do:

foreach ($_SESSION["addedToCart"] as $key => $val)
{
    if ($val["stoeltjes"] == $stoeltje && $val['film_id'] == $id) {
        unset($_SESSION["addedToCart"][$key]);
   }
}

easy way!? you can do this just with one foreach!

foreach ($data as $key => $subArr) {
    unset($subArr['1']);
    $data[$key] = $subArr;  
}

Can't be done with a simple command, but you can use a loop:

foreach(array_keys($output) as $key) {
   unset($output[$key][1]);
}

Have a look at the // comments

foreach ($array_leave_dates as $emp => $leave_type) {
  // you treat $leave_type as array here
  foreach ($leave_type as $leave_dates) {
   // you treat $leave_type as string here
   // doesn't feel right
   if($leave_type == 'Maternity Leave') {
     // you are unsetting with a value
     //unset($array_leave_dates[ --> $leave_type <-- ]);
     // i assume you want to delete the key 
     unset($array_leave_dates[$emp]);
   }
   else{
     // $row doesn't seem to exist, looks wrong from here
     echo $leave_dates[$row];
   }
  }
}

Try this:

foreach ($array as $key => $value) { 

    if ($value["userid"] == 4) { unset($array[$key]); }

}

The following code will do what you want:

<?php
$a = 1;
$b = 2;
$c = 3;
$d = 4;

$arr = array(
array ( $b, $d, $c, $a, $b),
array ($c, $a),
array ( $b, $d,  $c ),
array( $c, $d, $a, $b, $b)
);
echo "before:\n";
print_r($arr);

foreach($arr as $k1=>$q) {
  foreach($q as $k2=>$r) {
    if($r == $c) {
      unset($arr[$k1][$k2]);
    }
  }
}
echo "after:\n";
print_r($arr);
?>

Output:

before:
Array
(
    [0] => Array
        (
            [0] => 2
            [1] => 4
            [2] => 3
            [3] => 1
            [4] => 2
        )

    [1] => Array
        (
            [0] => 3
            [1] => 1
        )

    [2] => Array
        (
            [0] => 2
            [1] => 4
            [2] => 3
        )

    [3] => Array
        (
            [0] => 3
            [1] => 4
            [2] => 1
            [3] => 2
            [4] => 2
        )

)
after:
Array
(
    [0] => Array
        (
            [0] => 2
            [1] => 4
            [3] => 1
            [4] => 2
        )

    [1] => Array
        (
            [1] => 1
        )

    [2] => Array
        (
            [0] => 2
            [1] => 4
        )

    [3] => Array
        (
            [1] => 4
            [2] => 1
            [3] => 2
            [4] => 2
        )

)

As you can see, all the 3's have gone...

array_filter is great for removing things you don't want from arrays.

$cart = array_filter($cart, function($x) { return $x['id'] != 15; });

If you want to use a variable to determine which id to remove rather than including it in the array_filter callback, you can use your variable in the function like this:

$value = 15;
$cart = array_filter($cart, function($x) use ($value) { return $x['id'] != $value; });

We can make this more simpler. Just get all column values using array_column. Use array_filter with a custom callback to remove all empty string values. If after filtering, size of array is 0, then that key needs to be unset from all subarrays.

Note: The arrow syntax in the callback is introduced since PHP 7.4.

Snippet:

<?php


$data = array (
    'HeaderRow' => Array (
        '0' => 'Employee','1' => 'LaborHours', '2' => 0.1, '3' => 0.25, '4' => 0.5, '5' => 0.8
    ),
    'r0' => Array (
        '0' => 'Joe', '1' => 5, '2' => '','3' => '', '4' => 50, '5' => ''
    ),
    'r1' => Array (
        '0' => 'Fred', '1' => 5,'2' => 10, '3' => '', '4' => '', '5' => ''
    )
);


$cleanup_keys = [];
foreach(array_keys($data['HeaderRow']) as $column_key){
    $column_values = array_column($data, $column_key);
    array_shift($column_values); // removing header row value
    $column_values = array_filter($column_values,fn($val) => strlen($val) != 0);
    if(count($column_values) == 0) $cleanup_keys[] = $column_key;
}

foreach($data as &$row){
    foreach($cleanup_keys as $ck){
        unset($row[ $ck ]);
    }
}
print_r($data);