Unassociate File Types is a utility that helps you unassociate a file type
quickly in your Windows Vista or Windows 7 computer without the need to edit
the registry manually. Windows 7 & Vista do not provide a GUI option to
unassociate file types, thus the need arises for such a tool. The
user-specific association for the chosen file type will be removed from the
registry & the system will use the global file association settings. (in
System Utilities)