Broken links can be found in your webmaster tools where you created webpages and then you have altered their urls. The webpages show page not found 404 error. You can also delete such back links manually that present in your website.
Broken links are links that lead to pages that do not exist. When clicking on a broken link, the page you land on is called a 404 error page, a standard HTTP response that indicates that the requested URL doesn’t exist.