Delete book from iBooks

Hi,

I was wondering whether anyone knows how to delete one's book from iTunes (including ISBN, so it's no longer for sale) and close one's iTunes account. After countless emails to Support in the last weeks (because the book's up for sale but doesn't show up in any store, there's an error showing up on the sales page, seller name is wrong, etc.) and no reply whatsoever, I'm giving up.
Any advice would be highly appreciated.