PHP’s substr_replace replaces text within a portion of a string. In this case we only want to replace the last character with nothing. Here is the code sample:

$old_string = "My-Category-";
// remove the last hyphen from the string
$new_string = substr_replace($old_string,"",-1);
echo $new_string;
// should now read "My-Category"

This should replace the last character of a string with nothing.