The wiki page for uninstalling a packstack installation needs to be updated for Havana: http://openstack.redhat.com/Uninstalling_RDO
That document is a gross hack. It's fragile in the face of changing package names (or newly introduced packages), and it's just generally a bad idea. I'm nuking the page; the only sane way to "uninstall" openstack is to wipe and re-deploy your systems.