第一步：确认Cert-Name
Cert-Name 是Certbot眼中認得你交給他管理的域名(domain name)！
如果不知道
$ cd /etc/letsencrypt/renewal $ ls phpriji.cn.conf
第二步：删除这个域名
$ certbot delete --cert-name phpriji.cn Saving debug log to /var/log/letsencrypt/letsencrypt.log - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Deleted all files relating to certificate phpriji.cn. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -