You cannot close another application from within your own (an Android restriction).
The best practice is to restart your activity or use "StartActivityForResult" so the system handles the return.
If the other application isn't designed to return a result, you'll simply need to bring your app back to the foreground using "Intent" or "BringToFront".
This should bring your app back to the foreground.
Dim in As Intent
in.Initialize("", "")
in.SetComponent("com.votrepackage/.Main")
StartActivity(in)
If the other app supports returning results, use "StartActivityForResult(in)". When the other app finishes, Android will recall your activity with the result, and your app will automatically regain focus.
You can also use "Activity.BringToFront".