Does this exist?
Nay for forum posts, yay for blog posts.
After a post, you have 15 minutes(as shown) to edit it, after that, it is as-is. The option to delete the post remains permanent, there is a small X in the upper right hand corner of your reply.
If you simply want to redo it, or parts, you can always copy your reply before deleting it, then paste it in another "reply" and edit as you like. Any way you look at it the option to edit/delete is always present.