Docker error cannot delete docker container, conflict: unable to remove repository reference

There is a difference between docker images and docker containers. Check this SO Question.

In short, a container is a runnable instance of an image. which is why you cannot delete an image if there is a running container from that image. You just need to delete the container first.

docker ps -a                # Lists containers (and tells you which images they are spun from)

docker images               # Lists images 

docker rm <container_id>    # Removes a stopped container

docker rm -f <container_id> # Forces the removal of a running container (uses SIGKILL)

docker rmi <image_id>       # Removes an image 
                            # Will fail if there is a running instance of that image i.e. container

docker rmi -f <image_id>    # Forces removal of image even if it is referenced in multiple repositories, 
                            # i.e. same image id given multiple names/tags 
                            # Will still fail if there is a docker container referencing image

Update for Docker 1.13+ [Since Jan 2017]

In Docker 1.13, we regrouped every command to sit under the logical object it’s interacting with

Basically, above commands could also be rewritten, more clearly, as:

docker container ls -a
docker image ls
docker container rm <container_id>
docker image rm <image_id>

Also, if you want to remove EVERYTHING you could use:

docker system prune -a

WARNING! This will remove:

• all stopped containers
• all networks not used by at least one container
• all unused images
• all build cache

First, remove the container names

$ sudo docker rm backstabbing_ritchie

The result

$ sudo docker rm backstabbing_ritchie
  backstabbing_ritchie

delete the second part, which is listed on the container to be deleted

$ sudo docker rm drunk_feynman 
  drunk_feynman

Second, remove the container

$ sudo docker rmi training/webapp

The result

$ sudo docker rmi training/webapp  
  Untagged: training/webapp:latest
  Deleted: 54bb4e8718e8600d78a5d7c62208c2f13c8caf0e4fe73d2bc0e474e93659c0b5
  Deleted: f74dd040041eb4c032d3025fe38ea85de8075992bdce6789b694a44b20feb8de
  Deleted: 7cbae69141977b99c44dc6957b032ad50c1379124d62b7d7d05ab7329b42348e
  Deleted: abb991a4ed5e4cde2d9964aec4cccbe0015ba9cc9838b696e7a32e1ddf4a49bd
  Deleted: 1952e3bf3d7e8e6a9b1e23bd4142e3c42ff7f4b7925122189704323593fd54ac
  Deleted: f95ebd363bf27a7546deced7a41a4099334e37a3d2901fa3817e62bb1ade183f
  Deleted: 20dd0c75901396d41a7b64d551ff04952084cc3947e66c67bae35759c80da338
  Deleted: 2505b734adda3720799dde5004302f5edb3f2a2ff71438f6488b530b728ba666
  Deleted: 2ee0b8f351f753f78f1178000ae37616eb5bf241d4ef041b612d58e1fd2aefdc
  Deleted: 2ce633e3e9c9bd9e8fe7ade5984d7656ec3fc3994f05a97d5490190ef95bce8d
  Deleted: 98b15185dba7f85308eb0e21196956bba653cf142b36dc08059b3468a01bf35d
  Deleted: 515565c29c940355ec886c992231c6019a6cffa17ff1d2abdfc844867c9080c5
  Deleted: 2880a3395eded9b748c94d27767e1e202f8d7cb06f1e40e18d1b1c77687aef77

Check the continer

  $ sudo docker ps -as
  CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                    PORTS               NAMES                  SIZE
  78479ffeba5c        ubuntu              "/bin/bash"         43 hours ago        Exited (0) 43 hours ago                       sharp_wescoff          81 B (virtual 187.7 MB)