You can easily remove recent Documents Menu and RUN MRU by doing little bit with registry through this tip.
To disable The Recent Docs menu can be easily disabled by editing the Registry. To do this go to the following Key:
Now in the right pane, create a new DWORD value by the name: NoRecentDocsMenu and set it's value to 1. Restart Explorer to save the changes.
You can also clear the RUN MRU history. All the listings are stored in the key:
You can delete individual listings or the entire listing. To delete History of Find listings go to:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Doc Find Spec MRU and delete.