Release : 8.5
Component : UIM - INFRASTRUCTURE MANAGER
Customer unchecked all the boxes on the Name Services tabs of all hubs (and clicked Apply). Then removed the old hubs from each Hubs tab.
But before the customer was finished with them all, they started to propagate again so he rechecked the rest of the boxes in Name Services. After he checked back after some time, and the old names were gone.
Apparently it took more time than expected but the hubs did sync up and the old hub names were eradicated.