Hi Fernando, you are right about editing your server blocks in the sites-enabled files. Do you have access to the files under that directory? You have to comment out all lines related to SSL:

SSLEngine on
SSLCertificateFile /path/to/your_certificate.crt
SSLCertificateKeyFile /path/to/your_private.key
SSLCertificateChainFile /path/to/your_certificate.crt

Test the configuration:

$ sudo apache2ctl -t

If no error appears, you can reload Apache:

$ sudo apache2ctl graceful

But this is just a temporary solution. You actually need to clean up all your server blocks and remove the HTTPS (port 443) configurations, or link to the correct certificates if you want to continue servicing HTTPS. Why would you uninstall Let’s Encrypt in the first place? Sites without SSL are highly discouraged from being indexed by Google nowadays.