This is a little embarrassing, but I accidentally answered a question instead of commenting on an answer. It's kind of weird looking at my answer every time I look at the question, so I'm wondering; can diamond mods view and permanently delete deleted questions? (Is this better suited for Meta SO?)
No, diamonds cannot totally obliterate already-deleted answers. The only way for any content to be hard-deleted is for the devs to step in.
Well permanently, at least enough that anyone below 10k rep won't see it