Hogweed wrote:

I don’t want to get into 3rd-party tools to edit the nk2 file – I
just want to delete it and start again. But I haven’t got one! Yes, I
have my machine set to view all files etc, and have done a search on
*.nk2 and there simply isn’t one.

Open Windows Explorer, enter "%AppData%\Microsoft\Outlook" in the Address
field, click Go, and you'll see it whether or not you have viewing hidden
files and folders enabled.
--
Brian Tillman