code: public function deleteDictionaryItem($dictionaryId, $itemKey)
      {
          $url = $this->_getApiServiceUri(). 'dictionary/'. $dictionaryId . '/item/' . urlencode($itemKey);
          $result = $this->_fetch($url, \Zend_Http_Client::DELETE);
  
          return $result;
      }
docs: Delete single Dictionary item
  
  @param $dictionaryId
  @param $itemKey
  @return bool|mixed
  @throws LocalizedException