I believe that you are asking how to prevent that data from displaying, yes? If that is the case, then Aaron is on the right track.
To completely remove the ability to quickly display what recent documents you have opened (for whatever reason), right-click anywhere on the taskbar and click properties. Once in there, click the Start Menu tab, then click the Customize button.
Once in the new window, uncheck the box in the lower left corner of the window titled "List my most recently opened documents." This will remove that section of the start menu from being seen while logged in as you.
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I swear, troubleshooting is a science: the best discoveries are always on accident...