UK Landlord Forum / Life

a family member is renting out my wives flat. everything was verbal and he told us he wanted to leave. we gave him two weeks to get organised which he agreed to but now his girlfriend is back to him he said he is not leaving and he wants money from us for windows and boiler he put in which we asked him not to do. can i go round and change door locks when he is out and throw his belongings on the street..? plz help