<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def remove_user(self, user):
 """ Deletes a user from an organization. """

        org_user = self._org_user_model.objects.get(user=user, organization=self)
        org_user.delete()

        # User removed signal
        user_removed.send(sender=self, user=user)