By default, your recently opened documents is shown in “Start” menu.
For privacy, you may have felt the need of not showing your accessed documents in “Start” menu. To do that:
1. Right-click on taskbar and select “Properties”.
2. In the “Taskbar and Start menu Properties” menu, click on “Start Menu” tab.
3. Select the “Start menu” radio button and click “Customize” button.
4. In the “Customize Start Menu” click on “Advanced” tab.
5. Now uncheck “List my most recently opened documents” in “Recent documents” section.
Done. Now recent accessed documents will not be shown in “Recent Documents” of “Start menu”. Note that cleariing the list or unchecking the option will not delete the documents from you PC. Those files will not show up in “Recent Documents”. So you are safe.