@Wolfgang_Rosenauer Thanks Wolfgang, I did just that and it worked fine! I think it will be very handy to have Z-way available for any low-level Z-wave config stuff. I noticed there was a ‘Firmware update’ section, so could potentially be useful too for that (although most manufacturers don’t seem to like to distribute firmwares 
).
For anyone else interested, you have to use the Web interface (port 8083), Expert Z-wave Management mode, Devices, mark the device/node as ‘Failed’, wait 30s, then it appears in the list above where it can be selected and permanently deleted.