Had a similar headache with my Cerbo GX last month. Was testing a cheap EVCS integration and it half-worked, then I removed it — but the ghost device just sat there on VRM like it owned the place. Tried the usual stuff, restarting the Cerbo, clearing cache on the browser. Nothing shifted it.
Eventually found that doing a full VRM dashboard reset (the "reset to default" option in the dashboard customisation panel) nuked it properly. Lost all my custom widgets in the process which was annoying, had to rebuild everything.
Not ideal but it worked.
Bit different to your setup — I'm not running 3-phase or Pylontech, just a modest Fogstar Drift 200Ah LiFePO4 on a 12V cabin system with a Victron MultiPlus-II and a couple of SmartSolars. But VRM seems to handle ghost entries the same way regardless.
One thing worth checking — if you're integrating a wallbox via MQTT or Modbus, sometimes the device ID gets cached in Venus OS itself rather than just on VRM. Might be worth SSHing into the Cerbo and poking around in /data/conf or similar. There are some stored device configs in there that don't always clean up after themselves.
Anyone else had this with openWB specifically? Curious whether it's a Venus OS v3.7x thing or just how EVCS devices are handled generally. Feels like Victron's EVCS support is still a bit rough around the edges tbh.