I've long advocated editing privileges that would expire after a reply, but I'm not sure that that functionality is available.
You do have options, though. Although we cannot delete a post, we can edit it for a period of time--meaning that you could delete its contents if you needed to. I've accidently hit "submit" before completing a post too, so I know what you're saying. If it's just an unfinished post that you don't want to send yet, consider opening the Edit screen (pencil icon, lower left below your post), and deleting it. Perhaps replace it with a brief comment like "accidental post--stay tuned." Then rewrite your post and submit it again when you're ready. If you do not want to lose what you've already written, copy and save it to a text file before deleting.
It's a good habit to compose any substantial post in a text editor or word processor and then copy-pasting it into the EpicSki editing screen when it's ready. If you use BBCode (very simple-Google it if unfamiliar), you can do everything in a plain text editor that you can do with the EpicSki editor. It can save a lot of the aggravation of premature posting, losing your work when it vanishes into the ether (used to happen a lot, but the EpicSki editor is much more stable now), and such. And you can edit and delete to your heart's content before posting. A good idea, I say, as I type directly into the EpicSki editor, knowing better....