Face it squarely. Look right at it. It's there.
There is nothing you have to 'do'.
Think about it, about when it began, what your thoughts and fears were/are about what triggered the anger. Say it out loud or to yourself: "I am angry because (this happened)." and "I also feel hurt/afraid/disappointed/rejected/taken advantage of/left out.... etc" to help pinpoint what the anger is all about and what the triggering event means to you.
Write about it to help "put" it somewhere.
Know that it is temporary, as all things are.