Docker-backup dir growing large

We are using a cron job to make backups …
gitlab-rake gitlab:backup:create SKIP=registry
… as we do not care to backup our registry (docker images). However, the local disk space is slowly being consumed in /var/opt/gitlab/gitlab-rails/shared/registry/docker-backup, and it’s not clear how to control this.

Should we simply (perhaps periodically) delete this directory? Or is there some special backup command parameter that is supposed to take care of this?