Here’s what you don’t do: don’t do anything to disturb the peace. You have to move and you need to have a reference. No bowling balls etc. He may not care about the police but you have to because you need to find another apartment. Don’t leave anything near his door or anything that can be traced back to you. Don’t make noise. Don’t confront this asshole. He’s violent and almost certainly has a gun. What are you thinking?
I’d look at that lease hard. There’s got to be a noise ordinance clause. Write a letter to the landlord and tell him he’s got thirty days to cure the problem. If not, you will consider the lease broken and look for other housing. Put the ball in his court.
In the meantime, call the police non-emergency number and get the name of an officer. Tell him what’s going on. Some areas have an officer or department that handles community issues. This person basically does nothing, but they can document. Tell the officer you need documentation so you can break your lease. They’ll tell you what to do. Every time you make a police report, send a copy to the landlord. Keep writing the landlord a letter every week, including a journal of how often and how long this guy makes noise. Keep copies. Ask the police if anybody else is complaining about this guy. If they’re making a report, you can go down to the police department and get a copy of the reports made about this guy. Give copies to the landlord. You can say “he’s interfering with your enjoyment of your home.” You can also say due to the unlivable conditions, you have no choice but to break your lease, although you don’t want to. I’d also ask the landlord, what would you do in my situation? Ask in writing, it’s more likely you’ll get an answer in writing. If he says, just call the police every day, tell him that’s unacceptable and your home is unlivable. In writing.
If the landlord is so afraid of this guy he won’t do anything, you’re going to have to leave. But don’t do anything to mess up your own record. If you can get a free legal consultation, look up lawyers and get one. Write your questions out in advance. You get one hour. Tape the session, which is legal as long as you say you’re doing it. That person is not legally your lawyer, so don’t admit to wrongdoing or talk about doing retaliation. I’d ask, if I tell the landlord he’s got thirty days to cure it, can he do anything to me if I break the lease? Do I have to be out at the end of the thirty days? Whatever he says, pay attention. Don’t argue, you’re wasting your minutes. Just do it.
Look for another apartment and find out what it will cost. It’s better to be able to tell the landlord, I’ve already looked and I can get a similar or better apartment for the same money. Have addresses and amounts ready. There are a lot of vacancies now due to Covid, and a lot of tenants are behind on their rent. Scare him into thinking he’s going to lose all his paying tenants over one oaf.
If this guy isn’t thrown out (and maybe even if he is), leave. He’s crazy and you’re better off away from him.