The date_sub() is an inbuilt function in PHP which is used to subtract some days, months, years, hours, minutes, and seconds from given date. The function returns a DateTime object on success and returns FALSE on failure.

1. Code:

  <?php 
	function getDateSubWithFormat($dateStr, $day, $format = ''){
		if(!isset($format) && $format == '' ){
			$format = "Y-m-d H:i:s";
		}
		if (is_null($dateStr) || trim($dateStr) == '' || "0000-00-00 00:00:00" == trim($dateStr)) {
			return null;
		}
		try {
			$d = date_create_from_format($format, $dateStr);
			if (false === $d) {
				throw new \Exception ("Invalid date");
			}
		}catch (\Exception $e) {
			return $dateStr;
		}
		date_sub($d, date_interval_create_from_date_string("$day days"));
		$str = $d->format($format);
		return (false != $str) ? $str : null;
	}
	
	echo(getDateSubWithFormat("2022-06-27 01:12:22", 5, "Y-m-d H:i:s"));
    ?> 

2. Example:

Input:

"2022-06-27 01:12:22", 5, "Y-m-d H:i:s"

Output:

2022-06-22 01:12:22