Uhhhhh I guess hacknernews doesn't let you delete comments or even edit them (wtf??) But it looks like I read the previous comment wrong and responded to something that wasn't actually said.
You can edit a comment within during a certain period after initial creation (20 minutes, I believe). You can delete a comment during that time as well as long as no one has responded. You may have missed the edit window here, but you did the next best thing, make a comment with a correction or addendum.