I found this solution on StackExchange and it worked like a charm - thanks to user user3439894 ([https://apple.stackexchange.com/questions/372684/how-to-delete-kexts-in-catalina|source]):
When booted to '''macOS Recovery''' the '''Macintosh HD''' is not protected and '''you do not need to disable SIP!''' Simple boot to '''macOS Recovery''', open '''Terminal''' from the '''Utilities''' menu and use the following ''command'': rm -r /Volumes/Macintosh\ HD/System/Library/Extensions/AppleThunderboltNHI.kext -- It's gone! Reboot... Done! That said, I would have just renamed it, e.g. : cd /Volumes/Macintosh\ HD/System/Library/Extensions ; mv -v AppleThunderboltNHI.kext AppleThunderboltNHI.kext.original That way, then if need be it can easily be renamed back to AppleThunderboltNHI.kext