There is not a button to sort pages in a section alphabetically “out of the box”. I have also not come up with a ‘creative workaround’ either.
[If you have a creative workaround, please share it in the Comments below. I’ll add it as an update to this blog post and give you full credit!]
However, if you download and install a third party tool called Onetastic for OneNote, you can then install a Sort Pages macro that allows you to sort pages in a section in ascending or descending order.
Pro Tip: If your OneNote Notebook has password-protected sections, unlock the section before running the Macro or OneNote 2016 may crash. I found this out the hard way and hope this tip can help you avoid that grief.
For more information, please read: “What is Onetastic for OneNote and Why Should I Care?“.
If you are using OneNote for Windows 10 (Universal App):
There is not a one-click “Sort A-Z” button for Notebooks, Sections, or Pages at this time.
Tangent: There was a February 2017 update that allows you to sort your notebooks using drag and drop to reorder them.
The OneNote Windows 10 Universal App is regularly updated with new features.
I recommend you check back to the “What’s new in OneNote for Windows 10 – Office Support” every month to see if a one-click Sort pages feature is added.