The easiest way would be to not download any games in the first place. My DD always needs to get me to enter our ITunes/App store password so I only download games I approve of.
But yes, I agree with cward, an expensive item to just use as an MP3 player.
Agree too, DS has an ipod which has games on it, but as he doesn't (and won't) know my itunes/app password he can't download anything without asking me. He also knows he doesn't play the games unless he asked me first. As his is a older style he usually using mine to play games anyway, because they won't go on his.