How to Remove 404 Not Found URL?

[Vamp1re]

I am trying to remove my 404 URL through Google Webmaster tool but failed, i need help of you guys to remove that URLs .

[blessy_smith]

404 errors, especially ones for URLs that are being indexed or linked to by other pages pose a potentially poor user experience for your users. If they are landing on multiple 404 pages in one session, their trust for your site decreases and of course leads to frustration and bounces. Google does have a set crawl budget allotted to your site, and if a lot of the robot’s time is spent crawling your error pages, it doesn’t have the time to get to your deeper more valuable pages that are actually working.

Errors in sitemaps are often caused by old sitemaps that have since 404’d, or pages listed in the current sitemap that return a 404 error. Make sure that all the links in your sitemap are quality working links that you want Google to crawl. The best way to stop Googlebot from crawling URLs that it has discovered in the past is to make those URLs (such as your old Sitemaps) 404. After seeing that a URL repeatedly 404s, we stop crawling it. And after we stop crawling a Sitemap, it should drop out of your "All Sitemaps" tab.”

[aryanmarshall45]

Use the webpage removal request tool

[dennis123]

404 Not Found is an HTTP URL response code of a site. Websites are often respond to site visitors with a 404 not found error page when there is no user searching page in it. Similarly, search engines spiders including Google Search Engine spiders also found 404 not found pages when spiders crawl websites.
Read more (http://webdoubts.com/webmaster/remove-404-urls-google.html)

[fauzsp]

every1 can remove a link through webpage removal request you should use it and it will sort out your problam