Anger is an expression to show that someone isn't satisfied with something. Usually we all humans as well as animals have this feeling. I was a very angry bird in my school days, then I gradually realised that anger doesn't make any profits. But I didn't find any button to stop it & still I feel angry sometimes.

Now, what I do to calm down? Generally I use to sleep to maintain my anger, sometimes I listen songs.

But experts suggest some process to maintain anger. Such as :

Counting numbers : If you're feeling angry and wanna calm down soon then start counting number as per contra. It'll shift your concentration from the anger.

Go for a walk : It's also a good process to calm down your anger, whenever you feel anger just go for a walk to a cool place, better if you walk in a big garden.

Another good therapies are meditation, dance, eat your favorite food, visualise some positive thoughts atc. atc.. Overall, if you wanna calm down you have shift away from the object/subject that made you anger.