This is more or less a sequence of manual steps, because I don't want to remove volumes I might still need, especially if no containers are using those volumes at the moment.
This is also why I, sometimes, prefer the following over: docker volume prune.
In situations where I have literally thousands of docker volumes, basically after a long time of not removing any docker volumes, the following comes in handy.
At first I get the 200 (just some number) biggest docker volumes (as root).
I exclude containers, that contain postgres or redis in their names, essentially allowing the removal of all other volatile containers, named and unnamed.
# Just to show the format:
du -s /var/lib/docker/volumes/* | sort -k1 -rn | head -n 200 | grep -i -vE "postgres|redis"
# Output:
# 40120 /var/lib/docker/volumes/0e7aa18c73bec2379bef2adc077990d714c547c7b1719c95057db3443bb00d58
# 40120 /var/lib/docker/volumes/0e33840746b64e945c05730d8114b1097053464456a92806780a9eef57296f7e
# 40120 /var/lib/docker/volumes/0d9929b8d1b56a3b128df965c9fb42c4a6948cc058edfbb49b7f027bc3539ae8
# The actual command only returns the volume names:
du -s /var/lib/docker/volumes/* | sort -k1 -rn | head -n 200 | grep -i -vE "postgres|redis" | awk -F "/" '{print $NF}
# Output:
0e7aa18c73bec2379bef2adc077990d714c547c7b1719c95057db3443bb00d58
0e33840746b64e945c05730d8114b1097053464456a92806780a9eef57296f7e
0d9929b8d1b56a3b128df965c9fb42c4a6948cc058edfbb49b7f027bc3539ae8
Then, after checking the result of the above command, I remove the docker volumes:
docker volume rm -f $(du -s /var/lib/docker/volumes/* | sort -k1 -rn | head -n 200 | grep -i -vE "postgres|redis" | awk -F "/" '{print $NF}'