code: public function deleteSecondaryDnsDomains($domain, $domain2delete){
          $domain = (string)$domain;
          if (!$domain)
              throw new BadMethodCallException('Parameter $domain is missing.');
          $domain2delete = (string)$domain2delete;
          if (!$domain2delete)
              throw new BadMethodCallException('Parameter $domain2getInfo is missing.');
          try {
              $r = $this->delete('dedicated/server/' . $domain . '/secondaryDnsDomains/'.$domain2delete)->send();
          } catch (\Exception $e) {
              throw new ServerException($e->getMessage(), $e->getCode(), $e);
          }
      }
docs: Delete a domain on secondary DNS server
  
  @param string $domain
  @param string $domain2delete
  @throws Exception\ServerException
  @throws \Ovh\Common\Exception\BadMethodCallException