Whenever you create a new page in any of your OneNote notebooks, a date and time stamp is added to the page. This makes it easier to find and organize specific pages later on.
While it’s not currently possible to edit the page creation date in OneNote for the web, you can use the OneNote desktop app on your Windows PC or on your Mac to do this. For more information, see Change or remove the page creation date or time in OneNote 2016 for Windows.