So in 1984 I had a job as an assistant apt manager to supplement my income (I'd just gotten out of a second run at college and entry level accounting jobs didn't pay much). About a month into it, the owners got in a fight over management, two of the five owners had their own mgmt companies and one succeeding in talking the other partners into giving him the building. The other guy pulled the crew off the property in retaliation. The last thing the old manager did, on Sunday morning, was hand me a coffee can full of keys and tell me I was in charge. I ended up quiting the entry level job, and stayed in property management until I was pushed into retirement in 2009. On the whole it worked out pretty well.
I'm surprised your manager's contract doesn't specify that they have to get off the property if they are no longer employed there. I hope they don't cause too much trouble. Where are you? I'm in Washington state. If you want advice or just to swap war stories PM me.