I have never been a user of forums, so I am not familiar with their structure.

That's why it's always a good advice to spend some time reading them, taking a look at them, before start posting on them.

When I composed this message, the URL indicated I was on the suggestion box page

When you are composing, there is no indication in the url of the forum you are in. That info is shown in the box under 'category'.

I'm assuming this post is now in limbo, and I can't figure out how to delete it.

You can't delete it but it's not in limbo either. Just post the suggestion part of it in Suggestions Box.

So if you can delete this post, I would appreciate

Let's close it for now.