Unhandled promise rejection Error: Can't set headers after they are sent

I would like to make a if else return (for conrtole) but: "UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent. "

exports.delete = function (req, res) {
  Parking.findById(req.params.id).exec()
    .then(function (parking) {
      if (userController.ensureAuthorized(req, 'Director', parking.id)) {
        return parking;
      }
      return res.status(403).send({msg: 'unauthorized'});

    })
    .then(function (parking) {
      User.update().exec();
      return parking;
    })
    .then(function (parking) {
       return Parking.remove({_id: parking._id}).exec();
    })
    .then(function () {
      res.status(200).json({msg: 'Ok ! Parkink remove'});
    })
    .catch(function (err) {
      return res.status(400).send(err);
    });
};

Ty

via Kymz