Often times you want to remove all docker images and all docker containers. When you're experimenting with images, it gets a bit painful to manually remove each image / container individually.
To remove all containers:
docker stop $(docker ps -a -q)
docker rm $(docker ps -a -q)
To remove all images:
docker rmi $(docker images -q)
Now when you run
docker ps -a
All containers should be gone
Running
docker images
you might still see one or two images, these will probably require the -f flag to force remove them.