"(why no delete button?)"

I don't know of any forum system that allows users to delete posts. It's always an administrative thing.

In fact, you are better off just editing your post and just putting "[SOLVED]" at the start of the subject in future. At least then if someone encounters a similar problem, they can ask for clarification.

Common etiquette is to also say HOW you solved your problem for this very reason. Although this may not really apply to your question.

Cheers
Aaron