Cannot Delete Class from Campaign

Hmmm. Cannot delete a class from my campaign. (Franz created a half-orc at some point and he's only supposed to use Humans in my game), but because he gave it to someone, I cannot delete it and there's about 50 NPCs, but I don't know which one it is. There needs to be a way to delete a class and if there's an NPC or PC that's using it, provide options to handle that, ie change their race to a still existing one or delete the NPC altogether or show a list of affected NPCs with edit buttons where we can decide what to do with them.