I often suggest tag edits in which I add the homework-and-exercises tag to homework like questions. In some cases, these questions are closed as off topic even before my edit is reviewed. So, in that case, I think it is better to not bother the reviewers with my edit. Because if my edit gets approved, then it bumps the useless closed question to the front page. But there's no harm if it gets rejected. So shouldn't there be an option/feature to retract your suggested edit, like the one we have for flags?
There is no way to retract a suggested edit, as per this Mother Meta (where it was also suggested that users interested in such a feature should make a feature-request on Mother Meta, but I doubt anyone has in the 8 years since that answer was made).
I don't think that adding homework-and-exercises to a closed question is a big deal. Sure it'll push it to the reopen queue, but that queue doesn't fill up quite like the close queue does, so having an extra question to address shouldn't be a bad impact.