code: private static void deleteOldFeedItems(
        AdWordsServicesInterface adWordsServices,
        AdWordsSession session,
        Set<Long> feedItemIds,
        Feed feed)
        throws RemoteException {
      // Get the FeedItemService.
      FeedItemServiceInterface feedItemService =
          adWordsServices.get(session, FeedItemServiceInterface.class);
  
      if (feedItemIds.isEmpty()) {
        return;
      }
  
      List<FeedItemOperation> operations = new ArrayList<>();
      for (Long feedItemId : feedItemIds) {
        FeedItemOperation operation = new FeedItemOperation();
  
        FeedItem feedItem = new FeedItem();
        feedItem.setFeedId(feed.getId());
        feedItem.setFeedItemId(feedItemId);
  
        operation.setOperand(feedItem);
        operation.setOperator(Operator.REMOVE);
  
        operations.add(operation);
      }
  
      feedItemService.mutate(operations.toArray(new FeedItemOperation[operations.size()]));
    }
docs: Deletes the old feed items for which extension settings have been created.