Delete last 4 of credit card field from database

<?php
// originally http://pastie.org/8498705
// target form id 66, change to your form id
// set the priority on the call to 20 to make sure the payment gateway filters have all ran
add_action("gform_after_submission_66", "clear_cc", 20, 2);
function clear_cc($entry, $form){
    //the credit card field on my form is field id 4, and the credit card number part of the complex field will be 1, so field 4.1, change to your field, but leave the ".1"
    GFFormsModel::update_lead_field_value($form, $entry,"","","4.1","");
}