There is much discussion going on about Google's proposed tool to disavow links, but Bing is a step ahead and has already launched theirs.
Sign into Bing Webmaster Tools, click on the "configure my site site" tab and then select
There are options to discount links from a domain, a directory or a page. All you need to do is indicate which you want, and then enter the url and click "Disavow".
I feel sure that Google will now follow with their own tool very soon.