I think you’ve misunderstood the system. I’ll use Cleric as an example, here are the options available to you now:
Rank 1: Cleric
Rank 2: Cleric C2, Krivis, Priest
Rank 3: Cleric C2 (C3 if you have chosen C2 at Rank 2), Krivis (C2 if you chose Krivis previously), Priest (C2 if you chose Priest previously), Bokor, Dievdirbys
So on and so on. You don’t ever go back a class. You just get to pick between all the classes you unlocked (including the circles you’ve unlocked). In the end you can still pick up to only 6 classes (for now, it’ll change when there are more ranks), and can’t ever go backwards, or reset a class (not currently at least).