When privacy matters, sometimes it is important to clear what files or documents has been recently viewed in Windows 7.
Recently viewed files is a history that displays every documents opened and is located in Recently View Items of the Start Menu.

The good thing is that by default Windows 7 does not display the recently opened Item.

To clear it out this is what you do:

1. Right click on the Start Menu button or the Task bar.
2. Select properties

This will open the Properties of the Task bar and Menu Properties.

3. Uncheck the option Store and display recently opened programs in the Start Menu to clear the list of recently opened programs.
4. uncheck Store and display recently opened items in the Start menu and the task bar to remove the Recent Items history.
5. Click OK. That's it, You are done.