To delete a cookie we use the setcookie() function as if it were a normal cookie. The only difference is that we enter a past expiry date in our 3rd expiry date. In this way, the cookie is expired and is deleted immediately. As an example we will show this cookie 1 hour before saying time() - 3600 and the cookie will be deleted:

setcookie ('cookie', 'salute world', time () - 3600);