What can I do to get too much salt out of ham, after baked?

Soak it, the only way to get salt out of meat is to get it wet. It's not going to make the meat taste any better though so unless you really have to use it you're better off chucking it and putting it under "learning to cook a ham mistakes". Not saying you're a bad cook at all, we all make mistakes you know and oversalting is one you just have to learn from.