How to remove undesired topics automatically?

However interesting are Your news'/articles' sources - there is often possible that some part of those set You won't find worth reading. In that case You may often find a pattern (like some phrase which is repeatedly used in those posts'/articles' titles) - which could be used to avoid those in the future. You can do that with a filtering mechanism (in this case a rejecting filter).

In order to do that:

1. Open the sidebar and tap the pencil icon.
2. Find the feed which articles You want to adjust and tap on its name.
3. You should see a window called "Edit a feed". Choose a FILTER bookmark, then choose "+".
4. Select "REJECT", enter a keyword (or keywords) describing topic(s) You are not interested in. The best situation would be if You can point out a keyword which is repeatedly used within (the articles') title. For example, if You don't wanna read a series of articles which titles are beginning with "Deal of the day" - You could use it as a keyword phrase: Deal of the day. In this case choose that the filter should be applied to the title or link address. You may also choose applying a filter to the article's content - but this could be less effective and result in rejecting too many articles.
5. Go back twice (using the back button on the bottom of Your device or the arrow on the top left corner of the screen).

That's it! :) You may repeat this procedure for other feeds You subscribe and want to adjust - unfortunately there is no "global rejecting filter" yet.