apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/AdminService.java/AdminService/deleteApp
class AdminService:  @Transactional
  public void deleteApp(App app, String operator) {
    String appId = app.getAppId();

    logger.info("{} is deleting App:{}", operator, appId);

    List<Cluster> managedClusters = clusterService.findParentClusters(appId);

    // 1. delete clusters
    if (Objects.nonNull(managedClusters)) {
      for (Cluster cluster : managedClusters) {
        clusterService.delete(cluster.getId(), operator);
      }
    }

    // 2. delete appNamespace
    appNamespaceService.batchDelete(appId, operator);

    // 3. delete app
    appService.delete(app.getId(), operator);
  }