I was getting the error "leave federation cleanup failed. error 13 - confidentiality required" when trying to run the "vdcleavefed" command after a failed PSC installation.
I attempted to install 6.0 U2, but my current embedded vcenter was running U1.
So after the failed install, i wasn't able to decommission my failed PSC. So I just reattempted the installation with U1, and it worked!
Hope this helps someone.