Remove a FileDescriptor for notification of data available to read.

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