Here are my instructions for running the container:

docker run -p 5432:5432 --name=db -e POSTGRES_PASSWORD=secret -d --mount type=volume,src=postgres_data,target=/var/lib/postgresql/data postgres
docker volume ls

Here is the result:
0

And I verify that the container is running properly

And excute the

docker rm --help 

command then prompts me that this cmmand can remove the anonymous volume associated with the container:

1

Then I do this:

docker stop db
docker rm -v db
docker ps -a

Here is the result:
2

Although the container has been removed, the volume is still there and I don’t understand why:

docker volume ls

3

remove a container also removes the volume associated with the container