Log into your server via SSH as root and execute the following:
rm -rf /var/netenberg/fantastico_de_luxe/
rm -rf /usr/local/cpanel/whostmgr/docroot/cgi/fantastico/
rm -rf /usr/local/cpanel/3rdparty/fantastico*
rm -rf /usr/local/cpanel/base/frontend/*/fantastico
rm -f /usr/local/cpanel/base/frontend/x/cells/fantastico.html
rm -f /usr/local/cpanel/whostmgr/docroot/cgi/addon_fantastico.cgi