Can you list all the devices in MAAS, or go to the Machine details page where the container lives and see if the container is listed there? It may (or may not) be the case that Juju is not removing the containe, hence leaving the records there.
Can you list all the devices in MAAS, or go to the Machine details page where the container lives and see if the container is listed there? It may (or may not) be the case that Juju is not removing the containe, hence leaving the records there.