On Raspberry Pi – for use with HomeAssistant – this worked for me (per this post above) to remove an old cert that is no longer valid. The command is (run directly from the original folder I downloaded certbot-auto into):
./certbot-auto delete
This installed several new elements and python packages (taking a few minutes) before running the command and showing me the list of domains for which I was then able to easily remove the old one.
Thanks!