create a logout funcionality

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C#

C#4.0

I am developing a web app in vs 2010.
instead of using a button to logout from the webapp doing like this:

protected void btn_logout_Click(object sender, EventArgs e)
      {
          Session["User"] = null;
          Response.Redirect("Index_Page.aspx");
      }

I want to use only a simple text and hyperlink but i dont know how to redirect to the Index_page form by clicking this text and making session["User"]=null.

What to do in this case?