Php how to remove any last commas

rtrim for example:

$str = 'foo,bar,blah,bleh,';
echo rtrim($str,',');

// foo,bar,blah,bleh

rtrim('test,,,,,', ',');

See the manual.

completely different way:

$str = "1,2,3,4,";
$str = substr($str,0,strlen($str)-1);