NAME
        IND_REMHANDLER -- remove an input handler from the device

   FUNCTION
        remove a function previously added to the list of handler
        functions.

   IO REQUEST
        io_Message      mn_ReplyPort set
        io_Device       preset by opendevice
        io_Unit         preset by opendevice
        io_Command      IND_REMHANDLER
        io_Data         a pointer to the interrupt structure.

   NOTES
        This command is not immediate