Let's Encrypt won't stop autorenewing

Hello kind peoples.

I have a domain/website that I’ve been hosting for a while, secured with a Let’s Encrypt cert.
Up until recently auto-renewals have been going fine. Recently however the client’s IT people restricted the allowed CAs, so renewals started failing.
While I was working to get this sorted, they decided to take down the site altogether.

Before this decision was made, I set Let’s encrypt for the domain to manually renew only, so as to stop getting failure notifications. Nonetheless, failure emails still went out on the regular.
I then disabled the domain; no joy - still getting emails.
Deleted the domain - still getting emails.
Went into /etc/letsencrypt/renewal and deleted the .conf file for the domain - still getting failure emails.
Went into /etc/letsencrypt/live and deleted the listing for the domain - still getting failure emails.
I’ve rebooted the machine - still no joy.
Anyone have any idea what process is driving this, and how to get it to stop?

Where are the emails coming from?

From the server - same emails I’d expect to get if the domain was active and the renewal was