New user without Subscriber WordPress role

only Participant Forum role after login via FB social. How turn of automatically first role?

I have installed your plugin Super Socializer in my wordpress site. I use only FB social login to activate BB press forum. Everything is okay, but new user account which are create via social FB login has simultaneous WordPress role – Subscriber and Forum role Participant.

This second role is okay because give access to forum and this is enough I DON’T want create simultaneous user with worpdress Subscriber role.

How to turn off this option???