Question

How can I delete all the elements from an array, except for one in particular?

Answer 1

You can unset individual elements using the unset function:

unset($array['element']);

A quick way to do what you intend is to simply create a new array:

$new_array = array('element' => $old_array['element']);
unset($old_array);

Or use array_slice:

$new_array = array_slice($old_array, $offset, 1, true);