Select the Start Menu tab, followed by “Customize”
Select the Advanced tab, then uncheck “List my most recently opened documents,” and use the Clear List button to clear the current list.
How to disable document tracking permanently?
The above approach will clear your document list and prevent it from displaying under the Start Menu. However, a recent document history will still be kept in the background. To turn this functionality off entirely, you’ll need to edit your registry. Important: editing your registry and making mistakes can cause disastrous side effects, including leaving your PC unable to boot, so please proceed cautiously!
Select Start -> Run -> and type “regedit”
Open folders in the registry to navigate to HCU\Software\Microsoft\Windows\ CurrentVersion\Policies\Explorer