Help! How can I give my xbox account to my son.

Just has it says. My son recently turned 18. He is in his senior year of high-school. He's been playing on my Xbox account ever since he started playing games. All of his accomplishments are on that account. I just want to give him that account and start a new one for myself. How do I do this? Do I just change the email linked to the account? Do I have to change the email and username? I've been digging around online and haven't found much info on this. I can't be the only dad who is a gamer that has had to do this. Please help