Hi,
On your Samsung Galaxy S24, "Closed Notebooks" in OneNote are just leftover references to notebooks you previously opened, they don’t exist in OneDrive and can’t be deleted. To remove them, open OneNote, go to Notebooks, then long-press any closed notebook and select "Remove from list"; this only clears it from your app view. If that option doesn’t appear, try signing out and back in or clearing the app cache via Settings > Apps > OneNote > Storage > Clear Cache to refresh the list. This safely cleans up your app without affecting any real notebooks.
Kind regards,