I was an idiot and edited an answer rather than my question - how do I make sure my stupid edit never sees the light of day?
I rejected your edit suggestion (hope it was the one you meant - the comment was a good clue), so the edit won't be applied :)
But in general, you've hit on a small problem - there's no way to retract an edit suggestion as far as I know.
You can click the Edit button again and sort of undo your changes, but this is often tricky, especially if the text has formatting, so I don't recommend it unless the suggestion you made was very minor. Of course, this is the right action if you spotted a mistake in an otherwise good edit suggestion you've made (just not one you didn't actually want to make at all).
Another option is to ask someone to reject the edit - for example you could leave a comment for the post author asking them to reject your suggestion, or come to the Downboat or Ask Ubuntu General Room and ask folks there to reject.