[solved] Another instance of Certbot is already running

You need to kill the other certbot process.
You can do that by rebooting the box.
Or by killing the specific process.
To find the certbot process, try:
ps -ef | grep certb
The process ID would be the first number after the user, like:
root 5555 5100 …
To kill the process, try:
kill 5555
((replace 5555 with your actual certbot PID#))