You can uninstall RVssl Addon from WHMCS by:

1. At your WHMCS, go to Setup -> Addon Modules -> RVssl -> Deactivate.
2. SSH to your server as root, and run the following commands.

rm -rf /home/${user}/public_html/whmcs/modules/addons/rvglobalsoft

rm -f /home/${user}/public_html/whmcs/includes/hooks/rvglobalsoft_ssl.php

rm -f /home/${user}/public_html/whmcs/includes/hooks/rvglobalsoft_rvs.php

rm -rf /home/${user}/public_html/whmcs/modules/servers/rvglobalsoft_dedicatedip

rm -rf /home/${user}/public_html/whmcs/modules/servers/rvglobalsoft_ssl