User Configuration > Administrative Templates > Microsoft OneNote 2016 > OneNote Options > Other
User
HKCU\software\policies\microsoft\office\16.0\onenote\options
To disable the ability to embed files on a OneNote page, so people cannot transmit files that might not be caught by anti-virus software, etc. Note: This policy will only limit embedded files in the OneNote UI, if a page has an embedded file OneNote will still sync and replicate the embedded files in the file system.