First; Finding Broken Links:
To fix broken links, you need first to identify which links are broken. There are numerous different ways to find broken links. Use Google Webmaster Tools to set up a custom filter on your Google Analytics account for your 404 Error page. Also, you can manually check each link.
Second Fix Broken links :
Fix Broken External links: You can either remove them or replace them with valid links
Fix Broken internal link:
Identify whether it was caused by a typo or a misspelling.
Redirect broken link: use the 301 methods to redirect, or if not possible, to redirect with 301 then and then only redirect to the Home page.
Delete Broken link: Only delete If the broken link is genuinely not essential to your website,
first, find your all broken links from deadlink checker websites. If your website is WordPress then you install the redirection plugin.
give old URL and new URL in that plugin.
Your site URL will be fixed