And, I do not share the apple ID password. I think he is going on to a computer and browsing to AppleID.com. From there he puts in his Apple ID (which kids can see) and clicks on "forgot password". The only thing he has to do is Click "Allow Reseting of Password" on his iPad or cellphone. And, now I can't turn off Two-factor Authentification. If I could turn it off, then the only way he could change the password is to have access to the email account I set up for him (to which I only have the password).
Family Share is on and he is part of it.
I could delete his cell phone and iPad from his Apple ID account. But, won't that keep him from having the family share plan as part of the Family Plan?
If his devices are removed, he can't be part of Family Sharing.