Cannot remove deleted OneNote notebook from Windows 10

I am trying to delete old OneNote notebooks and end up with notebooks only on personal or work OneDrive "folders".

Somehow I have ended up with a "zombie" entry in Windows 10 OnenOte "recent" list . It always appears as a "selectable" notebook even though it doesn't exist.

The file reference is 

https://d.docs.live.net/< long hex string>/^.Documents/<one note name>

Now the directory name starting with the two characters ^. , "%5e.", isn't visible, even if I switch on "show hidden files" in Windows Explorer.

Can I delete this entry n the recent files list somewhere in the Registry, or some other way get rid of the reference to the "zombie" OneNote that doesn't exist - or maybe it does but I just can't get at it to delete it.

Thanks