I’ve done 2 things, with varied success rates. I will tell you that I have an open ticket with ST regarding ghost devices, and there seems to be a problem on their end. Here’s the last thing I was told:
I was finally able to speak with our development team regarding these devices.
The unfortunate news is that we do not currently have a solution, but we are working hard with a few parties to get this resolved. It turns out that this issue has pretty high visibility.
Let me know if you have any questions, I personally really appreciate your patience.
I would suggest contacting support with the ghost device’s ID and see if they can nuke it. Sometimes that does work.
I have also been successful by manually creating a device via the IDE, using the ghost device’s ID, and using the device type of zwave switch. Once created, I use the app to find the manually created device, and then I Removed it via the app. Since it won’t find the physical device, just force delete it.