I'm not an expert, but I know that AD is undoable. I also know from trial-by-fire that when you undo AD, you lose all of your user/group configurations and I think you have to revisit all your shares. I don't know if there's a MS or 3rd party utility for preserving such things so that you don't have to redo them all, or exporting AD users/groups and importing them into non-AD users/groups.