How to clear all credit card and token data within WHMCS database

[arnyphp]

I want to delete all credit card data and any remote token data stored in WHMCS.

So I tried using the 'delete bank' and 'delete credit card' buttons under settings, general, security. This didn't seem to do anything as I could still see some clients have data in the credit card fields within tblclients, i can also see entries in the deprecated table tblcreditcards, and there is also data in tblpaymentmethods

I used this on tblclients 

UPDATE tblclients
SET cardtype = '', cardlastfour= '', startdate = '', expdate = '', issuenumber = '', gatewayid = '';

and used phpymyadmin to empty tblpaymentmethods and tblcreditcards but in doing so, i noticed that a client had a payment, and that on the transaction list page, the 'payment method' field was showing as blank.

So I restored the DB from the backup I made beforehand, and thought I'd ask the question here rather than trying again and breaking things.

Thanks!