cleanup unused code

TV Player WPF/App.xaml.cs

@@ -1,7 +1,4 @@
-using DirectShowLib.BDA;
-using System.Configuration;
-using System.Data;
-using System.Windows;
+using System.Windows;
 using TV_Player.ViewModels;
 
 namespace TV_Player
@@ -18,5 +15,11 @@ namespace TV_Player
 
             base.OnStartup(e);
         }
+
+        protected override void OnExit(ExitEventArgs e)
+        {
+            _tvPlayer = null;
+            base.OnExit(e);
+        }
     }
 }