So a friend of mine (of course we've all heard that before) bought a macbook and wants to do a BTO option instead of what he chose. He is concerned about his information that he has on the macbook. Some business files, pictures etc. What does he need to do to make it so all his information is cleared off and he can return it with peace of mind? Bought at the apple store so I'm sure they will wipe it also but wants to be safe. Thanks.