Guest won't leave...

Try checking the direction your front door is facing. I found that my door was pointed inwards, (That is the arrows were). I reversed it and my guest left immediately. Hope that helps! :)

Make sure that the lot is set as residential. I had to change mine from generic to residential and move my family back in, it moves them out when you make the change.

Teach him a lesson ;) Lock him in a room with a fireplace and a pool >:)

Lol I had one that was being rude and wouldn't leave ( before I knew how to fix it) she made me so mad that I added her to the household via cheat with plans to torture her but :( she has really grown on me now.

Just had this happen to me this morning. Had a wedding then no one would leave. I just traveled with them to a park or whatever and went home. Basically just dropped them off there. When I came back they were all gone :)

Kill the stalker to make me happy >:) pwez? It's the only way...

Shift click with cheats enabled and reset sim.
This worked for me. But not after declaring him my enemy and fighting to try and make him leave. Instead he just angrily stomped about my house helping himself to my fridge leftovers and the guest room and entertainment areas.

I have all the expansion packs and no CC. I was experiencing a problem where Derek Mattson (when not Father Winter) showed up and wouldn't leave my Sims house. The ask Sim to leave option was not available. I checked and my sims home was deemed as a residential lot. I tried the cheat code: ResetSim which did not work. I tried to mean interactions, but my he would still not leave the home. Finally, I had my Sim travel to another lot to visit a neighbourhood Sim and Derek showed up. Then I sent my sim home and locked doors only to household and Derek Mattson did not follow my sim home. Finally I got rid of him! If you have this problem and noting works, before moving households try having your sim travel to another lot, your unwanted guest/visitor should not follow you back.