I don’t see any way, either in the browser or in a compatible client, to remove old news articles. I’ve used the Android news app, and feedreader and rss guard on my desktop. They allow you to remove articles older than x months, and this is global.
I have some feeds that publish several articles a day, and some that publish a few a month. If I set News to remove articles older than a month, I lose articles I haven’t read on some of these infrequent blogs. But if I set it to 6 months, the daily news sites end up with thousands of entries.
Is there any way to either manually prune feeds, or set the expiration on a feed-by-feed basis?