If you don't have plans to repost that listing ever again, then you can delete it from your saved listings. Just be sure not to delete the associated images since that would cause them not to display in your active listings.
I pretty much keep all of my saved listings though, you never know if you'll need them again even if its just to create a similar listing from. I just move the ones that have sold or I'm no longer selling into different folders that I created to keep track of them. Since Auctiva doesn't charge for storing saved listings, I have never felt the need to delete them. That's just me though.