Hello,
I don't manage DNS with CWP, they are all manage outside the server, and they point to the server.
I could give you a domain, but it won't exist anymore, that's the point. Still need one?
Just to make sure I was clear enough :
- Domain was pointed to the server, the certificate was working.
- Delete the domain from the DNS, and remove the domain from CWP.
- Let's Encrypt try, and fail (because the domain is not pointed to the domain anymore) to renew the cert.