ASP.NET webform routing with slugs

I'm routing my ASP.Net web forms as per below I'm also using slugs to clean the URL's. I've written below code in Application_Start event of global.asax.
routes.MapPageRoute( "MyRoute", // Route Name "mypage/{ID}", // Route URL "~/mypage.aspx"); // Web Forms page And handled page request like below
string productName = requestContext.RouteData.Values["ID"] as string;
and afterwards getting product details pulled from from DB and displaying it. But problem is the Slug which remains in URL. like
http://localhost/mysite/mypage/190
where 190 is the id of the product.
I want it as http://localhost/mysite/mypage
any clue???
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