I am in a somewhat similar situation. The people we asked to move in with us are causing a lot of stress and we are concerned that they may cause some damage to the house we rent. They are not on the rental agreement but we don't want to get the landlord involved.

My suggestion is to see if there is some inexpensive (or free) legal advise in your area. We have a county law office were people can come in and ask questions and if nothing else can be directed to the people they need to talk to. We found them by doing a web search.

It would be best if he just kept his word about moving out, but you can't count on that. What has to be done may take a few (or 30) days, but the longer you wait, the harder it will be and the longer it will take for the 30 days to be up.