code: public function deleteSecondaryDnsDomains($domain2delete){
          json_decode(self::getClient()->deleteSecondaryDnsDomains($this->getDomain(), $domain2delete));
          return true;
      }
docs: Delete a domain on secondayr DNS server
  
  @param $domain2delete
  @return bool true
  @throws Exception\ServerException
  @throws \Ovh\Common\Exception\BadMethodCallException