if (Request.Cookies["zxcookies"] !=
null)
{
HttpCookie
mycookie;
mycookie =
Request.Cookies["zxcookies"];
TimeSpan ts = new TimeSpan(0, 0, 0, 0);//时间跨度
mycookie.Expires =
DateTime.Now.Add(ts);//立即过期
Response.Cookies.Remove("zxcookies");//清除 
Response.Cookies.Add(mycookie);//写入立即过期的*/
Response.Cookies["zxcookies"].Expires =DateTime.Now.AddDays(-1);
}C# 清除coockies
原文：http://www.cnblogs.com/dullbaby/p/3515978.html
