With collection types like those provided in Doctrine you have methods like removeElement(). When using plain arrays we unfortunately don't have those useful helper functions.

What we can use though is a combination of array_search and unset:

if (($key = array_search($id, $arrayToClean, true)) !== false) {
    unset($arrayToClean[$key]);
}

Of course you can also move this into a helper method of your own.