Need to remove an account from iPhone 11 we have done it before but it had already been saved in my cloud

I brought this IPhone11 from a friend back in May of this year we talked with apple at that time. They said give it 30days. Done that and things were good till I couldn’t control or download any apps found out the account was saved in my cloud. I have made new accounts but not going to do it this time till I get the Hixon account clear again

[Edited by Moderator]