function UnregisterServer(const Is64Bit: Boolean; const Filename: String; const FailCriticalErrors: Boolean): Boolean;
Unregisters the DLL/OCX with the specified filename. If Is64Bit is True, the DLL/OCX will be loaded as a 64-bit image and unregistered in a 64-bit process. If FailCriticalErrors is True, the system will not display any critical-error-handler message boxes. Returns True if successful, False otherwise.