Hi,
Thanks for contacting us. One thing you can try to do is to free up memory on OneNote for Mac by deleting the cache files and the com.microsoft.onenote.mac folder. Thus, you can remove the cache via following the below steps:
-Sign out and close all office apps.
-Go to Finder, find ~/Library/Containers/ (press command + shift + G and enter this path)
-Find “com.microsoft.onenote.mac” folder, select and move it to trash
-Restart Mac and sign in
Kindly ensure all the notes are synced successfully to the cloud, or you can backup manually your contents before doing this step.
https://answers.microsoft.com/en-us/msoffice/forum/all/one-note-memory/55acb142-479c-4e22-97a7-dc5e3c078595
2. Check if your OneNote notebooks are saved as local files or online files. Local files are stored on your Mac and may take up more space than online files, which are stored on OneDrive. To save your notebooks online, follow the steps
2. Reduce the number of backup copies that OneNote keeps for your notebooks. By default, there are two backup copies, which means that every notebook will need triple the amount of space. You can change this setting in File > Options > Save & Backup, under “Number of backup copies to keep”. The default value of 2 can be changed to 1, reducing the space by one third.
These are the few solutions I can suggest to you now. I hope they help to resolve the issue.
Regards,
Sola
