I have a test server that I use to vet changes before making them to my main server. I'm working on figuring out how to add a GPU for Plex hardware encode, so I installed it in my test server and enabled the bind in the System Devices menu. All went well. I shut down my test server and removed the device.

Now, on boot, my test server throws a VFIO Bind error and won't start my VMs automatically. I know why - I didn't unbind the hardware before removing it - what I don't know is how to unbind it now. It no longer populates in the system devices menu.

You could delete the config/vfio.cfg file on the flash drive and reboot.