Yesterday, a friend I refered to the site asked me how he can remove his billing information from adroll. I asked him why he wants to do that and he told me it's simply because he is no longer comfortable with how AdRoll charges his account coupled with the fact that he can't view his balance on his AdRoll dashboard.
To cut the story short, I told him he can't totally remove his billing info. There must be at least one valid payment method on file. He became more worried..
I asked him if he has a debit card with zero fund, he said Yes. So, I suggested he adds the card as a new payment method. He did and this enabled the "remove" button option for the old payment info.
With this, he was able to remove his active billing info without closing his AdRoll account.