To remove items from the Most Frequently Used Programs list, right-click Remove from this list. However, when you run the program again, it may reappear on the list.
You can stop a program from appearing on the Most Frequently Used Programs list. No mater how often you use the program it will never appear on this list.
Click Start and select Run.
Type regedit and click OK.
Look for the registry key: HKEY_CLASSES_ROOT\Applications\
Under this key are a series of sub-keys representing the installed applications.
Choose the executable you do not want to appear on the list. (for instance Excel.exe)
Click Edit, point to New, and select String Value.