PHP: How to remove specific element from an array?

Use array_search to get the key and remove it with unset if found:

if (($key = array_search('strawberry', $array)) !== false) {
    unset($array[$key]);
}

array_search returns false (null until PHP 4.2.0) if no item has been found.

And if there can be multiple items with the same value, you can use array_keys to get the keys to all items:

foreach (array_keys($array, 'strawberry') as $key) {
    unset($array[$key]);
}

Use array_diff() for 1 line solution:

$array = array('apple', 'orange', 'strawberry', 'blueberry', 'kiwi', 'strawberry'); //throw in another 'strawberry' to demonstrate that it removes multiple instances of the string
$array_without_strawberries = array_diff($array, array('strawberry'));
print_r($array_without_strawberries);

...No need for extra functions or foreach loop.

if (in_array('strawberry', $array)) 
{
    unset($array[array_search('strawberry',$array)]);
}