How to clear session completely , so user can not return back after logout?

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C#

ASP.NET

Hi Expert,

In asp.net website i have use masterpage where i put one button for logout option.

On master page load event i write following code for button text(login or logout).

if (Session["session_log_id"] == null)
        {
            lblUserName.Text = "";
            buttLogin.Text = "Login";
        }
        else
        {
            lblUserName.Text = "<font color=#666666 size=2 face=Arial, Helvetica, sans-serif>Hi </font> , <font color=#822228 size=2 face=Arial, Helvetica, sans-serif>" + Session["session_logged_username"].ToString() + "</font>";
            buttLogin.Text = "Logout";
        }

On that buttons onclick event,i write code

Session.RemoveAll()

and redirect the user to Home page.

Upto this working fine for me.But after that when i hit back button it return to that page and show logout button again.

on each page load event i have write code like this to check wheather session is exist or not and prevent the unlogged user.

if (Session["session_log_id"] == null)
        {
            lblUserName.Text = "";
            buttLogin.Text = "Login";
        }
        else
        {
            lblUserName.Text = "<font color=#666666 size=2 face=Arial, Helvetica, sans-serif>Hi </font> , <font color=#822228 size=2 face=Arial, Helvetica, sans-serif>" + Session["session_logged_username"].ToString() + "</font>";
            buttLogin.Text = "Logout";
        }

How to clear session completely , so user can not return back after logout?


Thanks in advance......