There are lots of techniques indeed, maybe I can share two that are very efficient for me:
— Visualizing a big red RESET button and pressing it in thoughts. At first, in order to do it, I would have to close my eyes.
— Listening to the entirety of the most violent music I can find in my library, headphones on, loud enough to cover to surrounding noise and low enough not to burst my eardrums. When the music finishes, I’d feel entirely relieved.

I’m not saying these will work for everyone, however, it works at least for me, maybe for other people it will help.

(PS : I wrote a little article about that second method some time ago, if someone’s interested…)