code: public function removeAll()
      {
          $this->removeAllAssignments();
          $this->db->createCommand()->delete($this->itemChildTable)->execute();
          $this->db->createCommand()->delete($this->itemTable)->execute();
          $this->db->createCommand()->delete($this->ruleTable)->execute();
          $this->invalidateCache();
      }
docs: {@inheritdoc}