Information on removing a bad Z-Wave node from HS4
If a Z-Wave device fails, then the normal Z-Wave removal process will not work, as it may not power on or its Z-Wave radio is broken and cannot speak with your Z-Wave interface. Attempting to delete the device from your Devices page will not work, as the device will still exist in your Z-Wave interface and will be recreated the next time you manage your Z-Wave network. In these cases, the Remove Bad Node button can clear the malfunctioning device from your interface so that it is gone for good.
Access the Device Diagnostics page from Plugins > Z-Wave > Device Diagnostics