If you came across with the same error like me with the "Transaction Broadcast Error" while you're posting, just stop trying re-post again and again. Go back and check your Blog, you may find that the post actually had been submitted successfully. Just like my case shown as below:
By now, unfortunately, there's no way to delete the post, and what you can do is edit the content and update the post, just like what I'm doing now.
I suggest editing and updating the repeated content into a reminder like this to help the upcoming user to get away of this error.
I think deleting is no longer available if there is at least one upvote. Maybe even your own initial upvote will prevent it from being deleted.
Then yes ideally is to edit the duplicates to at least tell people that the duplicates were not intentional. Otherwise someone might flag you which is not a good thing.
Good luck steemians