Open your registry and find the key below.
Create a new binary value, or modify the existing value called 'NoRecentDocsMenu' set the value to equal '1' to enable the restriction.
Exit your registry, you may need to restart for the changes to take effect.
Key:[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
Value Name: NoRecentDocsMenu
Data Type: REG_DWORD
Data:(0=disable, 1=enable)
More info: http://support.microsoft.com/support/kb/articles/q181/3/42.asp
