apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/client/ApolloOpenApiClient.java/ApolloOpenApiClient/removeItem
class ApolloOpenApiClient:  public void removeItem(String appId, String env, String clusterName, String namespaceName, String key,
      String operator) {
    itemService.removeItem(appId, env, clusterName, namespaceName, key, operator);
  }