Find and delete tags - Keep 4 newest directory
find data/docker/registry/v2/repositories/*/_manifests/tags/ -maxdepth 3 -type f -printf '%T@\t%p\n'|sort -nr|tail -n+5|cut -f 2- -d " " | grep -v 'latest' | xargs -i rm {}
Re-config repo
docker exec <docker-name> registry garbage-collect /etc/docker/registry/config.yml --delete-untagged