How to free up space on docker devmapper and CentOS7?

Just run these three. No need to remove RUNNING containers.

1. Cleanup exited processes:

   docker rm $(docker ps -q -f status=exited)
   

2. Cleanup dangling volumes:

   docker volume rm $(docker volume ls -qf dangling=true)
   

3. Cleanup dangling images:

   docker rmi $(docker images --filter "dangling=true" -q --no-trunc)