Docker Prune images

The docker image prune command allows you to clean up unused images. By default, docker image prune only cleans up dangling images. A dangling image is one that is not tagged and is not referenced by any container. To remove dangling images:

$ docker image prune
WARNING! This will remove all dangling images.
Are you sure you want to continue? [y/N] y

To remove all images which are not used by existing containers, use the -a flag:

$ docker image prune -a
WARNING! This will remove all images without at least one container associated to them.
Are you sure you want to continue? [y/N] y