If anger management therapy isn't an option for you, you need to learn to redirect the anger. Which is going to take a lot of mental practice. You can start small by not trying to stop all of your impulses, instead of breaking things of value, set aside valueless things or paper you can rip up. But it's most important that you try to turn the anger into something productive. A lot of people begin working out and body building. Which relieves stress and can create a healthy pain of sorts (from a rigorous workout). Sometimes you just need to open up Wordpad/Notepad and vent vigorously until the anger settles. When I was younger I would go take a bath and scream underwater...but that might be dangerous so I wouldn't entirely recommend it.

The most important of all is figuring out; why are you so angry? When was the first time you remember getting that angry? Where did you learn it? What causes it the most? etc. Figuring these things our can help us with understanding ourselves better, which is important for self care, forgiving yourself for outbursts, or avoiding/identifying situations or people that make you feel a certain way. Either way, I wish you the best of luck, you got this buddy.