Remove "phantom" notebooks from "NOTEBOOKS TO OPEN"

Hello 

I Use Microsoft/Office 365 provide by by education employer. I make extensive use of OneNote with the Notebooks hosted on OneDrive/ Sharepoint servers. This all works well and does what I need. However, when I wish to open an existing NoteBook in the Windows 10/Office 365 desktop client, some of the Notebooks are "phantom" i.e. they don't exist as files on the OneDrive/Sharepoint server. The one thing these notebooks have in common is their notebook location/name:  https://<sharepoint server>/ <something else>/^.Document/<one note name> . The presence of the "^" character in the location indicates these Notebooks don't actually exist. Now a guess is they were notebooks I created when trying to understand Onenote - they were deleted - but somehow the link wasn't "cleaned up". Does anyone know 1. Where these "phantom links" are stored and 2. how to delete them so the only notebooks I see in Onenote are ones that actually are hosted on one of my MS365/OneDrive/sharepoint locations?

Thanks

Clive