Well , dead lik removal is a essential in a SEO dictionary . It gives a bad impression of your websites making it unprofessional and not maintained . Once your site is up and running, apart from adding new content periodically, it is a nice idea to check for dead or broken links. The tool that is really helpful for checking broken or dead link is
http://www.dead-links.com .
If you find a dead or broken link, simply remove that as those links will reduce the credibility of your website as a whole with respect to the visitors and also to the search engines.