Jonathan wants to know if there's an Android equivalent to DBAN (Derek's Boot and Nuke). He wants to be sure to wipe his older phones and tablets completely. Leo says that the problem is that solid state discs can't really be erased effectively. It's because of the wear leveling software that SSDs use. Leo says one thing he can do is turn on encryption. That way, it's just word salad across the entire drive.
One thing he can do is to get into recovery mode. Turn it off and turn it on with the volume up/home button (check Google for the specific device). It will wipe most of it. Though he'll never get all of it.