Echo posts are scheduled as posts when your original post is published. These posts are set up in your Queue. To access these posts, simply click on Queue and click on the Social to which the posts were published. Mouse over the post you wish to edit and the controls for that post will appear. You can edit the post, reschedule the post, share the post now, or delete the post.
Note: Twitter Echo posts cannot be edited. They will go out as Retweets of original content.