New payment on checkout not installed!?!

We had a customer get in touch and let us know his payment would not go through. When checking, I found that we now had a "Credit Card / Debit Card (Authorize.net) as one of the options for payment. We have never installed this, and it didn't exist before. Checking the payment modules, I see that Authorize.net (SIM) is not installed, and I have not been able to find any other options that has enabled this. The only payment options that are installed are cheque / money order and Paypal Payments Standard which is what we wish to have.Where the heck will I find how to delete this option from our checkout page? We're running Opencart version 2.0.2.0

Well, it wasn't the best way to do this, but found authorize.net settings in my database under the settings. After deleting those, the option no longer shows up in the checkout.