As anger is an emotion, it is, like all other emotions, controlled by your thoughts. Your feelings and emotions are created by the meaning you give to external events and are not caused by the event itself.
People who are angry tend to base their thoughts and beliefs on the following assumptions:
1) They have been harmed
2) The person who harmed them did this intentionally
3) The person who harmed them had no right to harm them and should have behaved better
By thinking that you are a victim of deliberate harm, you are guaranteed to evoke feelings of anger. By changing the way you think about external events using hypnotherapy, you can learn how to replace these negative assumptions with more helpful beliefs and learn strategies to help change your reaction to your thoughts.