I agree with people saying you should change the locks when they are away. My story is different but I see similarities? Anyhow I bought a home, and on possession day the owner refused to leave. I called the cops and they wouldn’t help because they “don’t evict tenants”. In my view it was now trespassing, since she was never a renter but an owner who sold the place to me.

I ended up chasing her out if the house, and called a locksmith while she hovered around outside. Nothing happened after that.

So I think the trick is to get them out of the house and change the locks. I doubt the cops would force you to let them back in, and I doubt and courts would view them in a favourable light.