destroy and set new cookie

I am trying to create a page where once i pressed a link, he will be directed to a page where previous cookies/session in the machine will be destroyed..

but i encounter prob in destroying the cookie/session...

my code to create cookie:

function GetCartId()
{
//generate an encrypted string and set it as cookie
if (isset($_COOKIE["cartId"]))
{
return $_COOKIE["cartId"];
}
else
{
session_start();
setcookie("cartId", session_Id(), time() + ((3600 * 24) * 2));
return session_id();
}
}


...> how can i use php code in other page to destroy this cookie and then redirect back to the main page to craete a new cookie ???

i tried to use time-60 to destroy the cookie and then use header back to the previous page to create new cookie.. but it is not working..


my code:
<?
setcookie("cartId","", time() - 60);
header ("location:activate.php");
?>

please advise.