$re = '/(\/\/)(\w+)(\s+)(JOB)(\s+)(\w+)?(,)([\w+=\w+]+)/m';
$str = '//ADBB503 JOB ,MSGCLASS=2,CLASS=P
//ABCD JOB Something,MSG=NTNG,CLASS=ABC';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php