remove a hackers access

how can i remove all duplicate apps/files/contacts, etc. I would like everything i do on/with my IPhone SE

to NOT be copied. I have a problem with a highly insecure, neurotic, and socially challenged family member who enjoys getting into my phone, so he can feel like “the man”. This person is insecure and needs to know what everybody is saying and doing at all times.If he can’t be a part of EVERYTHING…he feels neglected/disrespected/ abused. It’s a sad situation. Unfortunately, this person knows more about phones, computers than i do, has more money to buy programs, domain services, etc, doesn’t work (retired), and lays around all day playing with his iphone and manipulating electronic devices. I am unable to move, at the present time, and am living under the same roof. is it possible i can successfully remove this person from my phone? And keep him off it? legally! lol