Logout not redirecting to Login Page MVC

Question

I am trying to navigate to login Page(SSO) but i am facing some challenges.

I dont have any Login Page/Controller where i can navigate on logout i need to redirect to third party page(SSO) on logout.

In View :(_Layout.cshtml)

<a href="@Url.Action("Logout", "Home")">
<i class="fa fa-sign-out"></i>
<span data-i18n="Log Out">Log Out</span>
</a>

In HomeController.cs

public ActionResult Logout()
{
  // Delete the user details from cache.
  HttpContext.Session.Abandon();
  return Redirect(ConfigurationManager.AppSettings["LogOutUrl"]);
}

In web.config:

<add key ="LogOutUrl" value="https://ssointrad.dev.ipc.us.aexp.com/SSOI/request?request_type=un_logoffampsd;SSOURL=https://wpdcldwa00123.abc.xxxx.com/GPATdev"/>

Now when click on logout it redirects to : https://wpdcldwa00123.abc.xxxx.com/GPATdev/Home/Logout

How to resolve this issue ?

Thanks.