array_walk_recursive itself cannot unset values. Even though you can pass array by reference, unsetting the value in the callback will only unset the variable in that scope.
<?php
/**
* http://uk1.php.net/array_walk_recursive implementation that is used to remove nodes from the array.
*
* @param array The input array.
* @param callable $callback Function must return boolean value indicating whether to remove the node.
* @return array
*/
function walk_recursive_remove (array $array, callable $callback) {
foreach ($array as $k => $v) {
if (is_array($v)) {
$array[$k] = walk_recursive_remove($v, $callback);
} else {
if ($callback($v, $k)) {
unset($array[$k]);
}
}
}
return $array;
}
?>
An up to date implementation of the above function can be looked up from https://github.com/gajus/marray/blob/master/src/marray.php#L116.