Deactivate previous session

Hello Anu,

If you are using form-based authentication then you need to do below to make sure your session will kill when you log out from syste,

protected void SignOut_Click(object sender, EventArgs e)
{
    
    Session.Clear();   
    Session.Abandon(); 

    // Sign out the user from Forms Authentication (if applicable)
    FormsAuthentication.SignOut();

    //Clear all cookies including authentication cookies
    HttpCookie authCookie = new HttpCookie(FormsAuthentication.FormsCookieName, "")
    {
        Expires = DateTime.Now.AddDays(-1), 
        HttpOnly = true
    };

    Response.Cookies.Add(authCookie);

    Response.Redirect("~/Login.aspx");
}