You can close any notebook that you’re no longer actively working in (for example, when a project is completed).
Note: Closing a notebook does not automatically delete it. It merely removes the name of the notebook from your list of recent notebooks. For more information, see Delete a notebook in OneNote for Mac.
Do the following:
To see your list of notebooks, if the Navigation button is off ( ), click the Navigation button to on ( ).
Click the Notebooks list dropdown arrow that appears above the section and page lists. You may need to click the name of the current notebook to see the list of notebooks.
Hold the Control key while clicking the name of the notebook you want to close.
On the menu that appears, click Close This Notebook.
Tip: If necessary, you can reopen a closed notebook again at any time.