No, my implementation (it’s still a WIP) doesn’t support sending “Update"s and “Delete"s yet. It’s one thing that bothers me about ActivityPub. Webmention is so much simpler in that regard. There also seems to be no way of forcing Mastodon to refetch an activity object other than sending an “Update” or “Delete” activity.
Just a small note: I deleted my Microblog.pub instance. I liked this piece of software and it’s a nice single-user alternative to Mastodon, but I don’t need a Fediverse instance anymore. My new fediverse strategy is to use my normal blog to post stuff (you can follow me via @email@example.com and @firstname.lastname@example.org) and Miniflux to follow people (Mastodon offers RSS user feeds).