code: function destroyRelation(model, relations) {
    if (!model) {
      throw new Error('No model provided.');
    }
    return _destructure2['default'](model, relations).then(function (destructured) {
      var relations = destructured.relations;
      return _transact2['default'](model, function (transaction) {
        return _relate2['default'](model, relations, 'delete', transaction);
      });
    });
  }
docs: Destroys relations on a model.
  
  @param {Bookshelf.Model} model - A bookshelf model instance
  @param {Object} relations - An object containing the relations.
  @return {Promise.Bookshelf.Model} The updated model.