I'd be interested in knowing that too, J, seems that they've really embedded Google and Facebook into everything. Made the mistake of linking my contacts with Facebook, and now my Facebook "widget" isn't working, and all I've got are dozens of old Facebook posts and older profile pics that won't update. (*sigh*)
Welcome to the forum. Two ways you can do this. If you can get your facebook on your phone working, go into it, hit your menu key then select settings. Scroll down to "Sync Contacts", hit that and you can choose to not sync with contacts. If you cannot get facebook to work then go to your phone menu>settings>accounts & sync>click on your facebook account and turn off sync.