With current update, there are now 2 ways to make Josef leave the House. First is by insulting him when he's smoking at the the House's Entrance on Friday. Second is to make him cheat on Anna with Isabella.
( 1st Method ) Buy a Beer from Store inside the Mall on any day. Meet Josef at the House's Entrance on Friday and you'll open a small conversation with him. Click the Chat Bubble logo on the bottom right of your screen and give him the Beer and there'll be small conversations again. Do this process ( Buy and Give a Beer ) 3 times / 3 Fridays, choose the right dialogues and Josef will leave the House:
1st : How could I forget?
2nd : She's a bit older than me...
3rd : Anna and I have been doing Starmaker > Anna let me play with her boobs > You're a loser, Josef
( 2nd Method ) Make sure you meet Isabella at the Beach on Thursday first to make her come to your House. Then go to Josef's Office and you'll see him chatting with Isabella. Go to the Mall straight away and Isabella will give you an offer to impregnate her. Accept it and go to the Hotel at the Downtown's Street on Thursday. After that, go to Josef's Office again the next week on any day ( except Friday ) and tell him that Isabella seduced you.
Josef then will ask you to drive him to the Hotel on Thursday and then you have to force him to have a threesome with Isabella. After that, exit the Hotel Room and Josef will tell you that he feels guilty for cheating on Anna. If I remembered correctly, you'll then see a dialogue indicating that Josef will leave the House because of guilt.