Feb 03, 2015 01:05 PM|Careed|LINK
You don't actually remove the cookie. You have to force the cookie to expire so that when it is read on the client, it will be passed its expiration date and will be removed. Then, when you go back to the server on your next request, the cookie will no
longer be available.
By deleting the cookie on the server, you only force your next request to send back the cookie that's still there, thus having the cookie come back to the server.
Set the Expires property on your cookie to either DateTime.Now or something like DateTime.Now.AddSeconds(-60) so that it will be clearly passed the expiration time when the cookie returns to the client.