Not too often would you need this, but I just ran into a situation where it was handy to get AD off an existing, but inactive, domain controller. Â I couldn’t get dcpromo to uninstall the services and demote the darn thing, because this server thought it was still active in the domain. Â I had physically removed this server and manually cleared it from the active domain. Â Why would you do this, well, that’s a long story, but I wanted to, let’s just say that.
Here’s how you demote a DC with dcpromo, forcefully.
“dcpromo /forceremoval”
I did this on a 2008 Server, worked great! Â All these years and I hadn’t needed to do this, and didn’t even know it could be done. Â Always something new to learn, huh!