I let go of my anger.

A kettle whistles until it is taken off the heat. It isn't being difficult. Whistling is the entire function, and the noise stops when the thing causing it is addressed, not when somebody shouts at the kettle.

Anger tends to work the same way. It is carrying information — usually that a line was crossed, or that something you needed went unnoticed. Anger that gets heard, said out loud to somebody or even written down properly once, quiets faster than anger that gets suppressed and then reheats every few weeks. Releasing it is often less about letting go than about finally listening to what it came to say.