<script runat="server">
protected void Page_Load(object sender, EventArgs e) {

    try
    {
        Response.Cookies.Clear();
        Server.Transfer("login.aspx");
    }
    catch (Exception exc)
    {
        Console.Write(exc.Message);
    }
        
}
</script>

<script runat="server">
protected void Page_Load(object sender, EventArgs e) {

    FormsAuthentication.SignOut();
    Server.Trasfer("login.aspx");
        
}
</script>

FormsAuthentication.RedirectToLoginPage();