Docker Registry 2.0 - how to delete unused images?

Question

We updated our private docker registry to the official Registry 2.0. This version can now delete docker images identified by a hashtag (see https://docs.docker.com/registry/

Answer 1

I host regestry in docker container with name docker-registry_registry_1 from image: registry:2

I just run garbage-collect with -m

docker exec docker-registry_registry_1 bin/registry garbage-collect /etc/docker/registry/config.yml -m