You need to open your multiplayer.ini or json with notepad and find entries for parc ferme. there are a couple of them, look for MULTI entries and find the one that you can set to '0' close server first.
Hm, just found out Parc Ferme is ON by default and needs to be set properly in the RFM when creating the vmod: http://www.race2play.com/homepage/show_posts/27986