$re = '/(\d{2}(\d{2})?\/\d{2}\/\d{2}(\d{2})?)|(\d{2}:\d{2}(:\d{2})?)/';
$str = 'Log Started
Created Date: 01/01/01 Time: 01:01:01 Start
Added resources at module on 01/01/01 01:01
Module 2 excecute
Resource depleted at 01:01 n pieces
Open 01/01/01 01:01:01 Log to refer
Target end date of new resource 01/01/01 approved
Log Ended. Result OK';
$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