How to delete file when session ends?

I have the following code in my Global.asax file.

1 void Application_End(object sender, EventArgs e)
2 {
3 //Get a reference to the currently logged on user
4 MembershipUser crntUser = Membership.GetUser();
5 //' Determine the currently logged on user's UserId value
6 Guid crntUserID = (Guid)crntUser.ProviderUserKey;
7
8 string strUniqueFile = crntUserID.ToString();
9 string newFile = Server.MapPath("~/Membership/PDF_Out/" + strUniqueFile + ".pdf");
10
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