Deleting is quick and there is no undo. The order below takes ten minutes and keeps everything that turns out to matter later - and something always does.

Take a copy first, of more than the files

  • Files and database, obviously.
  • Mail. Deleting hosting deletes the mailboxes, and the messages with them.
  • The DNS zone. Export it. Rebuilding thirty records from memory is a bad afternoon.
  • The certificate and any keys, if anything else depends on them.

Then check what points at it

A site being removed is often referenced by something that is staying: a form that posts to it, an image hot-linked from another site, a cron job on a different server, an API a mobile app still calls. Search for the domain before it stops answering.
grep -rn "old-site.com" /var/www/ --include="*.php" | head -20

Leave a redirect, not a hole

If the content moved, redirect it. A 301 keeps the standing the old address earned and takes visitors to the right place; deleting it drops both.

server {
    server_name old-site.com;
    return 301 https://new-site.com$request_uri;
}

And if it is genuinely gone

Return 410 rather than 404. It says "this existed and is deliberately gone", and search engines drop it faster and more cleanly than a 404 that might just be a mistake.

The order

  1. Copy everything, including mail and DNS —
  2. Verify the copy opens — Not that it exists - that it opens.
  3. Put the redirect or the 410 in place —
  4. Wait a fortnight — Watch the log for anything still asking.
  5. Then delete —
Do not cancel the domain at the same time. Keeping the name for another year costs little and keeps the redirect working, which is the part visitors actually meet.