Is anger necessary to surviving in this world? If you didn't have it, would you be defenseless against evil people? Good question.
I think the answer depends on what you mean by anger. Do you mean the feeling of it? If so, you have no need to worry. You can't help but feel it. You will never get rid of it permanently. It is a fact of our physiology and the world as it is: When you feel trespassed against, you will feel anger, at least to some degree. And unless you live on a deserted tropical island, you will be trespassed against in this life. Many times.
So perhaps we need to talk about the expression of the feeling of anger. Is the expression of anger useful? That depends on how you do it. If you express it with a fit of rage, it's probably not only not useful, it is usually counterproductive. But if you feel angry, and you meditate, and when you have calmed yourself well and you feel at peace, you think about the situation and try to think of a solution that does not cause more agitation, pain, or stress in this world than already exists, and if that is your expression of anger, I'd say expressing anger is very useful indeed. This is possible, even if you think you have an "anger management problem." It just takes the decision to think. And you can't think worth a damn when you're feeling upset. So you have to calm yourself first. There are many ways to relax. Meditation is one of them.
Some people don't want to calm down first and think. They are afraid that after they think about it and calm down, they won't want to do anything about it, which means they'll become a wimp, a doormat, and people will walk all over them. They believe they need their anger, and they need to express it freely.
Anger is a seductive emotion, and all the thinking you do in a state of anger will involve how to cause pain, make others feel bad, and make sure everyone knows you're the one who is "in the right." In other words, every solution you come up with in a state of anger will only escalate the situation and cause you trouble. People might back off, but they'll resent you and take future opportunities to bring you down.
The rarest but sanest response to anger is to calm down. And then think.
Be rare. Be your best self. Be a force for good in this world. Do not participate in perpetuating the hateful, angry, self-righteous actions of this world. Rise above it by calming yourself deeply and thinking before you act.
Adam Khan is the author of Principles For Personal Growth, Direct Your Mind, and co-author with Klassy Evans of How to Change the Way You Look at Things (in Plain English). Follow his podcast, The Adam Bomb.