退出登录，清除Session

 1 protected void Button1_Click(object sender, EventArgs e)
 2    {
 3        if (Session["UserName"] != null)
 4        {
 5            Session.Remove("UserName");
 6            Session.RemoveAll();
 7            Response.Cookies["UserName"].Expires = DateTime.Now;
 8        }
 9        Page.RegisterStartupScript("","<script>window.top.document.location.href='index.aspx';</script>");
10    }