Try this command below :
$ docker rmi node
that should work.
If you want to see the containers jus tuse this command :
$ docker ps -a
If you wish to remove all the containers use thsi command ;
$ docker rm $(docker ps -aq)
Hope this helps :)
If you think you need professional help to get an idea about how docker is used in production environment and in the industry think of getting docker training course, it will help you out in this matter of fact.