I ever made same thread about letting go my anger towards my former bullies some time ago.

Gus1234U gave this method: https://forums.psychcentral.com/copi...-emotions.html

And I read this method somewhere in PC, unfortunately I forget which thread:
1. Take deep breath for 4 seconds
2. Hold it for 5 seconds
3. Release for 8 seconds.

Through that's not really let go of my anger, it could calm me down for a moment.