If a page on your website no longer exist and you want to redirect it to your new page or website then you can use the .htaccess file for redirection.
Redirect from a specific page to a domain:
RewriteEngine on Redirect 301 /mypage.html http://example.com
Redirect from a page to another page:
Redirect 301 /oldpage.html /newpage.html
Now, whenever you open the url http://example.com/oldpage.html, it will automatically redirect you to http://example.com/newpage.html.