Sometimes you may be required to work offline and sometimes you just like to work offline! So in either situation, here is how you can sync and un-sync your work manually rather than leaving syncing set to Automatic in OneNote 2013.
Follow the steps below to learn how:
In Sync Status, select Work Offline | Sync only when I click Sync All.
Verify that your status is Not Connected.
You can now make any edits or changes and not have your work sync before you would like.
Once you have finished working offline, if you have not manually un-synced your Notebook, you will automatically re-connect and sync your work automatically, including sharing your Notebook to a SharePoint site.
To manually return to syncing, simply select Sync Status | Sync All or Sync Now.