code: public function deleteInstance($serviceName, $idInstance){
          if (!$serviceName)
              throw new BadMethodCallException('Missing parameter $serviceName (OVH Cloud Project).');
          if (!$idInstance)
              throw new BadMethodCallException('Missing parameter $idInstance (OVH Cloud Project Instance ID).');
         
         try {
              $r = $this->delete('cloud/project/'.$serviceName.'/instance/'.$idInstance)->send();
          }
          catch (\Exception $e) {
              throw new CloudException($e->getMessage(), $e->getCode(), $e);
          }
          return $r->getBody(true);
      }
docs: Delete Instances of Project Cloud Public
  DELETE /cloud/project/{serviceName}/instance/{instanceId}
  
  @return
  @throws \Ovh\Cloud\Exception\CloudException
  @throws \Ovh\Common\Exception\BadMethodCallException