yii\db\ActiveRecord::delete PHP Method

    public function delete()
    {
        if (!$this->isTransactional(self::OP_DELETE)) {
            return $this->deleteInternal();
        }
        $transaction = static::getDb()->beginTransaction();
        try {
            $result = $this->deleteInternal();
            if ($result === false) {
                $transaction->rollBack();
            } else {
                $transaction->commit();
            }
            return $result;
        } catch (\Exception $e) {
            $transaction->rollBack();
            throw $e;
        }
    }

 public function delete()
 {
     foreach ($this->answerVariants as $model) {
         $model->delete();
     }
     parent::delete();
 }