cvv
Arcane
If you got a separate key for the beta and final release, then you can go steam -> help -> steam support -> games, software, etc. -> search, choose kingdom come beta -> I want to permanently remove the game from my account
But if it was a single steam item purchase, or a single key, then you can't remove beta without also removing game proper.
This time around someone with a brain in their head got back to me saying they'll remove the item "as a courtesy".
Now here's hoping they know if they remove the Beta the regular game is gone too :D
Eh, at least I'd have a reason to buy a GOTY next year.