can you just run a few commands for me please (as root ) - what I'm trying to check is what your previous admin used.
history | grep letsencrypt
This just looks through the history for any commands that used letsencrypt. If there are some it will give us a clue as to what was used previously.
crontab -l | grep "letsencrypt\|certbot"
This just checks your standard cron for any commands for letsencrypt or certbot ( the new name for letesncrypt).
can you also check if the folder /etc/letsencrypt exists ? as this will again tell us if it's likely that the letsencrypt client was used.