If people have been living in your building for 10 years without a rent increase, do not give them a rent decrease. You need to bring them up to market. The first thing you do is provide a 90 day notice that they will be paying their own utility bill. Then a year later, you start inching up the rent. For now, make every tenant show you their ID and get ever adult 18 and over to sign a new month to month lease stating they will be paying the utility bill on the starting date you provide. If there are any you want to get rid of, serve them with a notice of termination. Your new management will be the start of a lot of moaning and groaning as you signal the end of the gravy train. But it is your building, not theirs. You are not running a rent subsidy, halfway house or a homeless shelter.