When you make a changes to your web site, the live version often gets out of synch. with the cached version of your site which resides on Google. When the Googlebots crawl a site they store a record, a snapshot in time, into a cache file.In the example above, from an organic Google search, there is a link to the cached copy, now if the link no longer exists the person browsing will be faced with a 404 error ( and not everyone creates a custom 404 page ) and this will also show up as a dead link which may impact your SEO performance.
There is a solution at hand – Google’s URL removal tool, which is part of the Webmaster Tools suite. Simply enter the name of the dead URL and Google will remove it..the process does take a few days but it is a great way of keeping your cached version of your site clean to both give your browsers a more pleasurable viewing experience and assists to optimize your site.