Can't sign out of Apple ID on iPhone

When you go to my settings where I sign in my Apple ID and you click it then it shows your Icloud, iTunes etc

down below is “sign out”. I can’t click sign out. Below the “sign out” it says “you can’t sign out your Apple ID because your phone is being restored.”

what does this mean?

what should I do to sign out?

I want to sign out because I want to give my phone away to a friend

[Re-Titled by Moderator]