How to delete Docker images and reclaim disk — rmi and image prune

Old images are eating your disk and you want the unused ones gone.

docker rmi myapp:1.0          # fails if a container still uses it; -f to force
docker image prune            # dangling only (safe)
docker image prune -a         # ALL unused — re-downloads hurt on slow networks

Docker Cheatsheet one-page card — commands that actually work — The full one-page card — Docker Cheatsheet. Get the complete cheatsheet on GitHub