$str = '123,333,234,';
echo rtrim($str, ',');

<?php
$text = "/t/tThese are a few words :) ... ";
$trimmed = rtrim($text);
// $trimmed = "/t/tThese are a few words :) ..."
$trimmed = rtrim($text, " /t.");
// $trimmed = "/t/tThese are a few words :)"
$clean = rtrim($binary, "/x00../x1F");
// trim the ASCII control characters at the end of $binary
// (from 0 to 31 inclusive)
?>