404 Error Pages "Page Not Found" How to Remove Them

Actually 404 Error or "Page not found" is just an indication for a link such like as "The link is present in indexed data for server realisation but server is unable to understand currently what was requested or it might be possible that the current links didn't crawled by search engine crawlers."For example when some one search for a particular page in search results or directly put in borwser's Url bar and HTTP server code in response redirects the users for the status of the request As "Page Not Found." Critically concern for "How to remove them"
     In case of having a lot of 404 errors for a site, actually not it is but problem is the links to these 404 error pages as having a lot of 404 error pages redirects a bad sign for the quality of a site .You need to find out where these links are on your site and then figure out who (which script) is creating them. You have to literally found them for internal, external and specifically if they are your own, what pages link to 404s to figure out for fixing the problem. In case of having most of your own links, then you should correct them. If they're external links, and particularly if they link to content that has moved, you should redirect.Obviously after bringing any change like removing, moving or content transfirmation with links already showing in search results, you need to use a proper server redirect strategy to correctly directed both search engines and users to original url destination. But the links are they key - not the 404, but if they're not your links, then I wouldn't stress on it.So the links encountering 404 problem for removing or moving the contents on your site from one location an other, it will concern to have the imagination for search engines crawlers of content similarity or duplicate content placed on two different locations, that means you didn't use the proper redirects for the current change.
     For the most of site using the disqus plug in on their sites, It might not even be real links. There is a thread here about users with the disqus plugin on their site. It puts some sort of session id (a number anyway) in a place in the javascript that makes Googlebot *think* it might be a link, so Googlebot goes ahead and crawls it.Here I also recommends you to use Xenu to crawl out site for metioning your own links for correction and redirect the wrong pattern to correct the urls.