Had something similar happen to a buddy of mine. His son deleted a bunch of his raid weapons, exotic weapons, and other stuff. He was upset but, knew it was his fault for not password protecting it or making his son his own account. His son is 5 btw. I would password protect mine and create him his own account and let him him pick out the logo. This way its his and he will want to play on his instead of yours. My daughter doesn't play on my PS4 because I got her a wii u but, if she ever starts I will password protect mine that moment. It sucks but, what else can ya do?