How can I delete a mistakenly added tag from an image in a private Docker registry? The option -rmi doesn't seem to work for remote images in Docker 1.9.1.
user@ubuntu-user:~$ docker --version
Docker version 1.9.1, build a34a1d5
user@ubuntu-user:~$ docker search myregistry:5000/user/image
NAME
myregistry:5000/user/image:20160119
myregistry:5000/user/image:20160119-20160120
user@ubuntu-user:~$ docker rmi myregistry:5000/user/image:20160119-20160120
Error response from daemon: could not find image: no such id: myregistry:5000/user/image:20160119-20160120
Error: failed to remove images: [myregistry:5000/user/image:20160119-20160120]