Hi,
Sorry about the docker login stuff, I wanted to remove this before posting the response, but I forgot.
I looked at it in more depth, and unfortunately I realized that deleting images from the registry won’t work easily out of the box. The reason for this is the following: To delete images from the registry the registry requires the delete action. We use our API as authentication and authorization server for the registry and our API does not handle the delete action at all at the moment. I thought it might be possible to add another authentication source to the registry, but I also looked into the registry configuration for the authentication section (https://docs.docker.com/registry/configuration/#auth), and unfortunately one can only register a single authentication provider.