A family of Microsoft products that enable users to capture, organize, and reuse notes electronically.
Dear User 234,
Thank you for reaching out to the Microsoft community. We are delighted to offer our assistance.
Regarding your concern, the .onetoc2 file is a table of contents file that OneNote automatically creates to keep track of the sections and pages in a notebook. It is normal for OneNote to create this file, and it should not cause any issues.
However, if you are experiencing multiple .onetoc2 files being created for the same notebook stored online, it could be due to a syncing issue.
If your OneNote files are stored locally on your computer, you can move them to OneDrive and manually delete the duplicate .onetoc2 files from your folders and subfolders. Ensure that no OneNote app is running in the background (check Task Manager).
If the issue persists, please let me know and we can explore other solutions. Have a great day.
Sincerely,
Sean | Microsoft Community Moderator