Was at a dealer on Saturday for an event. Got a few minutes with their head tech. He says you have to pull the triple tree top which then means the forks have to be re-aligned to reassemble. I'll have the dealer do it when the bike goes in for inspection and fork seal replacement (and hopefully nothing else.)
Eventually, I'll learn how to do this (and more) as I go along. But doesn't sound like something I want to dig into currently.
FWIW, the nut has a threaded flange on the bottom which is larger O.D. than the body of the nut. It's pretty clear to me that the top piece (Ducati calls it a "Steering Head") I think you guys typically refer to it as the "Triple Tree." Or am I misunderstanding what the Triple Tree is?