I don't think Feedly is necessarily doing anything wrong. Publisher beware kinda comes with the territory like making sure you don't accidentally send too many emails. It's kind of a quirk of centralization that you would have the recourse of "sorry, can I unsend that?" with the pubsub model to begin with.

But I agree that it would certainly be nice if they offered a way to delete content. For example, an interesting attack on a website would be to silently add spam to their RSS feed knowing it will be stored in RSS aggregators forever. That doesn't seem great.