.net自身具有一个清除Cookie的方法：

Response.Cookies.Clear();

但有些时候发现执行了该语句后Cookie仍然存在，因为该语句并不是物理删除Cookie，这里提供一个让浏览器帮助我们删除Cookie的方法：

1。删除所有Cookie

        int n = Request.Cookies.Count;

        for (int i = 0; i < n; i++)
        {
            HttpCookie myCookie = Request.Cookies[i];
            myCookie.Expires = DateTime.Today.AddDays(-1);
            Response.Cookies.Add(myCookie);
        }

2。删除指定Cookie

       //这里假设指定的Cookie为OtherInfo

        if (Request.Cookies["OtherInfo"] != null)
        {
            HttpCookie myCookie = Request.Cookies["OtherInfo"];
            myCookie.Expires = DateTime.Today.AddDays(-1);
            Response.Cookies.Add(myCookie);
       
        }

下面在说一下.net新增Cookie的方法：

        //添加Cookie，名称为UserInfo

        HttpCookie myCookie = new HttpCookie("UserInfo");
        myCookie.Values["userName"] = Request.QueryString["p"].ToString();
        myCookie.Expires = DateTime.Now.AddMinutes(5);
        Response.Cookies.Add(myCookie);

        //添加Cookie，名称为OtherInfo

        HttpCookie otherCookie = new HttpCookie("OtherInfo");
        otherCookie.Values["otherName"] = Request.QueryString["p"].ToString();
        otherCookie.Expires = DateTime.Now.AddMinutes(5);
        Response.Cookies.Add(otherCookie);