The standard full moon release: write down what you want to be rid of, read it, burn it, and do not keep the ashes.

The pairing with the waning half of the cycle is consistent across a lot of traditions — add while it grows, remove while it shrinks. The mechanism claimed is symbolic, and the one that is testable is ordinary: naming a thing and physically destroying the paper is a well-worn technique in therapy too, where it is called an expressive writing exercise.