Until sign-ups close, you can delete your sign up without any mod intervention. It's an accepted practice. I did it for shipswap when I saw I wasn't matchable.

I can't see any offer info beyond the numbers. However, I know what I requested and offered, so I know that right now the only fandom I could match on is HL. Since I do a lot of exchanges, I'm familiar with a lot of the other players' preferences. None of the other players are likely to be offering Richie or Ceirdwyn, and I figure both my Methos pairings are obscure enough that no one is offering them. So, I guess I'm not *certain* about matchability, so much as reasonably confident in the odds.

Re: the person requesting Duncan/Tessa: it occurred to me that there might be a definitional conflict. You think the request is an accident because their other requests are for gen or slash stories. I wonder if they're treating "gen" as a category that includes non-explicit stories about pairings. That's how I learned the term, and it's a definition I still catch myself using.