I'd like to know as well. Never seen a button, and right now I'm getting de jure wars declares on me by the kingdom of Lotharinga. Please help! I'm losing a buckload of money on mercs for defending me each time. And I basically just want to remain duke. I don't care about owning the lands. I can just give it to the king, but it's unsure if I'd actually remain that way, even though he likes me more than his dukes (yet can't stop attacking me).