I'm not sure about completely removing it, as I haven't tried it before, but wouldn't it be sufficient to just unpublish the game service? Leaderboards can be deleted individually (at the bottom of their settings page). I don't know about achievements.
No, it's not possible delete game overall. Once you published your app, it can't be delete it from the Market. The only thing you can do is unpublish the game, like Habakuk wrote.