I have written articles on how to start using RealmD and SSSD for integrating ubuntu into a windows network. However, prior to that I wrote an article on using PBIS. RealmD and SSSD is, by far, the superior method IMHO and experience, so for all of those folks that want to switch, you probably want to get rid of PBIS on a bunch of servers. To that end, I just wanted to drop a line (for myself and anyone else that needs it) on how to remove an existing PBIS install on a server.
Thankfully, PBIS did make it pretty easy, the two following commands will get you there:
sudo /opt/pbis/bin/uninstall.sh uninstall
The first command disconnects/unjoins your server from the domain. The second command removes PBIS.
There is probably some additional cleanup that can and should be done as well but I think that the above will at least clear the way for working with SSSD and RealmD.