Click EDIT, and click Go advance if you're on QUICK edit mode. A option for deleting the post will appear.
Check it again, It's beside the quote option. It'll stay for 8 hours after your post. You can't edit after it has been disappeared.
Like Agni said.. Click on Edit > Go Advance > Delete Post. But again, this Edit option is available only for 8 hours after posting.
You aren't late, 8 hours haven't passed yet. Thought, I'm not sure, if one can delete post once a reply is made