Declined Card in Stripe Test Mode

I am getting this error when trying to process a test transaction in ProSites:

Your card was declined. Your request was in live mode, but used a known test card.

I read in the Stripe settings to manually clear the associated row from the *_pro_sites_stripe_customers table for the given blogid to prevent errors on checkout or management of the site. However, I am not sure how to do that. I have looked in the DB but can't seem to what I am looking for.