protected function _deleteThumbnail($oArticle)
    {
        if ($this->canDeleteThumbnail($oArticle)) {
            if (!$oArticle->isDerived()) {
                $oPicHandler = \OxidEsales\Eshop\Core\Registry::getPictureHandler();
                $oPicHandler->deleteThumbnail($oArticle);
            }

            //reseting field
            $oArticle->oxarticles__oxthumb = new \OxidEsales\Eshop\Core\Field();
        }
    }