certbot certificates
# find the path to the fullchain certificate you wish to reinstall
certbot revoke --cert-path /etc/letsencrypt/live/... #path to the cert from above
certbot delete --cert-name yourdomain.com
rm -Rf /etc/apache2/sites-available/000-default-le-ssl.conf #or whatever the name of the apache conf you had it configured on 
rm -Rf 000-default-le-ssl.conf #or whatever the name of the apache conf you had it configured on
sudo apache2ctl restart
certbot #follow the guide to setup the new certificate