To remove the Manage option from the context menu of My Computer in Windows 2000/XP/2003 follow these steps:
Open Registry Editor.
In Registry Editor, navigate to the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
Create the following value (DWORD):
NoManageMyComputerVerb
and give it a value of 1.
Note: As always, before making changes to your registry you should always make sure you have a valid backup. In cases where you're supposed to delete or modify keys or values from the registry it is possible to first export that key or value(s) to a .REG file before performing the changes.
Close Registry Editor.
There is no need to reboot if you update your desktop by running gpupdate /force from the Run command (XP and Windows 2003).
Done!