Let's Encrypt plugin allows automated SSL certificate for those account which do not have valid SSL certificates.
Login to SSH of cPanel Server to install Let's Encrypt use following command -
/scripts/install_lets_encrypt_autossl_provider
/scripts/install_lets_encrypt_autossl_provider
To disable and uninstall the Let's Encrypt plugin-
/scripts/uninstall_lets_encrypt_autossl_provider
/scripts/uninstall_lets_encrypt_autossl_provider
To use Let's Encrypt please goto WHM >> SSL/TLS >> Manage AutoSSL
That's it!