We all have a reservoir of anger, some of us have a much bigger one than the rest, but we all have it in some capacity. I invite you to be silent for a few minutes and focus on your breath.
Pay attention to taking a breath in while counting to 3,4 or 5 then pause for a bit and exhale for the same count. After doing it a few minutes, scan your body in your mind, and search for any area in your body that is tense. In your mind bring your breath there until you feel that the tension has disappeared.
Once you are fully relaxed and in a meditative state-meaning your brain waves have slowed down, and your focused inwards, ask yourself this question: Is there a part of me that wants to come out that is angry? . You may get your inner child, or your teenage self, or an adult part of you that is angry at something. Ask more questions, why are angry? what hurt you? Who hurt you? What can I (Your adult Self) do to make you feel better? If you want to scream (the part in you that is angry) go right ahead. Do whatever it is that will make this energy in you get out of your body and release.
Afterwards talk to this part of reassure it that you will not let that happen again. Get up and shake yourself off. Jump around or dance if you want to. Give thanks to yourself for doing it, perhaps if you are more metaphysically advanced you can invite your higher-self to do it with you.
You can do this for any reason, not only anger. You can invite a Joyous part in you, to celebrate. Remember, we are all made up of energy. The clearer and cleaner the energy, the easier it is to stay positive and joyous.
Wishing you fun in this journey.