It is possible to use a string instead of offset, eg if you want to deletre the entry $myArray['entry'] then you can simply do it like this:
<?php
array_splice($myArray, 'entry', 1);
?>
Note that you can use unset($myArray['entry']) as well but then, it doesn't enable you to remove more than one entry and it doesn't replace anything in the array, if that's what you intend to do.