Moved house but Alex keeps discovering my old devices

I used to have Alexa working via node-red. I thought I had switched to the official plug-in, but honestly can't remember. I am now setting things up on a new Mac in a new house. The Alexa plug-in is doing everything that it should be doing when it gets a discovery request, but instead of those devices being discovered, all of the old node-red connected devices get discovered.

I have tried everything in the trouble-shooting guide and more - removed Alexa from all iOS devices; switched off all Alexa devices in my house; removed all Alexa devices via the web interface; removing just one Alexa device via the web interface; waited 10 minutes more times than I care to count; removed the Alexa Indigo Skill etc. But every time I hit discover devices, the phantom node-red devices reappear.

There is definitely no node-red server running anywhere. The old Mac that used to run the server is switched off.

Any advice?

And then finally I figured out the last thing I needed to do which was to disable the Node-Red skill. Now sorted. Sorry for the utterly pointless thread.