Create Cookie , request cookie and delete cookie

Create Cookie:

 HttpCookie login=new HttpCookie ("userdata");
 login["username"] = username_txb.Text;
 Response.Cookies.Add(login );

Request cookie:

HttpCookie login = Request.Cookies["userdata"];
string username = login["username"];

username_lbl.Text = "Welcome " + username;

Delete cookie using expire date:

 HttpCookie myCookie = new HttpCookie("userdata");
 myCookie.Expires = DateTime.Now.AddDays(-1d);

 Response.Cookies.Add(myCookie);