The credit card is not bound to the ipad, but to the corresponding Apple ID. The method of unbinding is as follows:

Step 1: Open iTunes software, click STORE in the left column, enter the homepage of the mall, click Login in the upper right corner, enter Apple ID(iTunes account) and password, and then click ID.

Step 2: On the account information page, select "Modify" at the end of the payment method line.

Step 3: Select "None" and finally click "Finish" to finish unbinding the credit card.