All packages need to unmount, remount, and uninstall package instances, and the entire package cleanly. All packages should do this through the APM callback mechanisms.
Documentation on how to do this will be added to the tutorial.
We need volunteers to help with this goal. I think all the infrastructure is in place to have packages clean up after themselves to greatly improve the experience of users, especially those just looking at OpenACS who create experimental instances of packages and want to clean them up.
I will bring this up at the next OCT meeting, but I think this will need to be addressed by package maintainers where possible, and the OpenACS developer community overall.