pier is full of old containers. Remove them, keep web running, and keep every image.

List everything:

Remove the old stopped web server. Its image stays:

docker rm old-web

Try to remove the image web uses and read who blocks it:

docker rmi nginx:1.27

Remove the running scratch container in one step:

docker rm -f scratch

Remove every remaining stopped container (answer y):

docker container prune

Confirm web is still up and all three images remain:

docker ps -a
docker images