How to delete/unset a cookie on php?

Question

I want to unset/delete my existing cookie with this:

setcookie (\"user\", \"\", time()-1); 
unset($user);

But cookies can not be deleted or

Answer 1

setcookie ("user", "", time() - 3600);
//will reset cookie(client,browser)
unset($_COOKIE["user"]);
// will destroy cookie(server)