Question: Is there a fast way to unassign a price group or promo group?

Answer:
Price/promo groups must be unassigned manually.

1. View items in the Item Updates Manager and expand to show the group in question.
2. Select the items to be removed from the group.
3. Right-click and select Change Price Group.
4. Select Undefined at the top of the list. This will remove the items from the group.