A little at a time. No need to get rid of it all at once and risk hurting someone. Just try to do something that calms you down or brings you joy. Some people exercise or run when angry. Some write. It all depends on you.
A good way to let out anger is to take a deep, slow breath and let it out slowly until you feel a little calmer. You can also write your thoughts and feelings on paper and you will start feeling better as you write. Go to http://www.ehow.com/how_2342758_let-out-anger.html for details.
Breath. Slowly calmly, especially in a public place with friends or strangers. If your all alone in an isolated place(preferably anyway) scream it all out, that is whichever you think would work better.
Well I have anger issues so I punch or kick the closes thing to me (human or not) which I don't suggest doing cuz it hurts them. I would try breathing or running. Some kind of activity that calms u down. U have to find something that helps u everyone is different.