$re = '/\s+\[.*?(?=\S+$)/m';
$str = '15-16-00-014716 AND15- [ ] (5) Description of 16-00-014715
15-16-00-014716 AND15- [ ] (5) Description of 1600014715';
$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