Remove a FileDescriptor for notification of data available to write.

def removeWriter(self, selectable):
        """Remove a FileDescriptor for notification of data available to write."""
        try:
            if selectable.disconnected:
                self._writes[selectable].kill(block=False)
                del self._writes[selectable]
            else:
                self._writes[selectable].pause()
        except KeyError:
            pass