$re = '/.*time\s+(\d{2}:\d{2}\s(am|pm)).*/';
$str = 'there is some text and maybe some number or symbols time 12:32 am and there is some text';
$subst = "";
$result = preg_replace($re, $subst, $str, 1);
echo "The result of the substitution is ".$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