You can either remove or archive a piece of content.
Unlike removing stream content, archiving preserves all the history associated to the content
If you don't mind losing the historical stats of some content and want to remove it, here's how to do it.
Select your engagement program, then click on the Streams tab.
over the content you want to remove, click on the gear icon when it appears, andfinally
That's it! Now you know how to remove a piece of content that has no history.