To add or delete credit card details, a client should navigate to his profile page by clicking his profile picture or name in the top-right of the page.
If the client account is American, the "Credit Card Details" box will appear below the Intro Box on the left side. If the account is from any other country, it will appear in the center below the Intro Box.
To add a card - click the "Add Card" button and fill in the details as prompted.
To delete a card - click the red trashcan icon on the right side of the details you'd like to remove.