In Metro Publisher, you can configure both Content and Events to be removed from your site at a set expiration date under Admin > Settings > Content.
This is especially useful for Events that are out of date.
If internal and external (manually added) links are pointing to those Events or other pieces of Content, they will return a 404 page and a so-called "crawl error" in Google analytics reports.
It is generally believed that 404 errors affect SEO. This information is false. Google will not penalize your site for 404 errors.
"Many (most?) 404 errors are not worth fixing. Here's why:Sort your 404s by priority and fix the ones that need to be fixed. You can ignore the other ones, because 404s don't harm your site's indexing or ranking."
Please visit the corresponding Google Support document for more information: Google Search Console Help - Crawl Errors report (Websites)
Create a custom 404 page by following the guidelines in this document: Using Pages to Create a Custom 404 Page
The goal is to improve user-friendliness and keep readers engaged on your site, so provide them with links to interesting landing pages or content on your 404 page.