My child change everything in his Apple ID and now he locked his self out and we can’t get back in
How do I sign out of his phone and make a new one
To regain access to a locked apple account, you can visit this website:
https://iforgot.apple.com/password/verify/appleid
For more information on how to regain access to your account, you should look at this article:
If you forgot your Apple ID password - Apple Support