I have a H9 that was upgraded from Core to Max. What is the proper way to selling it so that it gets disassociated from my account so the new user can associate it with his account? It would still be a H9 Max for the new owner, right?
Yes, your H9 will still be a Max for the new owner. You should open up H9 Control with the H9 connected, click on the Pedals button in the bottom menubar, and use the 'Deregister Stompbox' function to deregister it.