Yes, you are right, anger is a often a mask for unresolved hurt and childhood wounds. In the work I’ve done with clients I use a variety of techniques ranging from: self-examination (Byron Katie’s The Work), journaling, meditation (heart-based awareness, breathing, TM), somatic movement, sometimes EFT. It will depend on the client as to what modality works best.
The antidote to anger is of course: self-love, self-compassion, empathy, patience, kindness and equanimity. It involves developing a new dialogue with oneself.
Anger turned inwards can be the most destructive and may lead to illness and disease if not examined. Anger floods the body with toxic chemicals, so awareness through meditation of where the anger is stored in the body is very useful. All the best!