I looks like you are in Cali which is a notoriously tenant friendly state.

I know in Virginia my friend had a similar issue (side-by-side duplex, though, not second floor) and he was not proactive, just warning them several times verbally.

Just wanted to say a warm and friendly hello to all in the community.

Best part is NJ is not what its made out to be in terms of landlord friendly, the state gets portrayed as the entire state being bad when really most wacky laws are in the major cities and they apply to 5 units or more.  2-4 unit multi families fly below radar per say. 

I like how some people have said change the word “mentor” with “friend”.

We live in different worlds my friend.

In north/central NJ, 95% of serious arms-length real estate deals (i.e. not wholesales or  family/friend), attorneys will be assisting.

Hire an attorney and proceed with the eviction.In the future, I recommend you don't accept "landlord references" from friends or family members.

NY is a very tenant friendly state, so if he doesn't leave and she's on a month to month.

Thanks...from all of your REI friends.