Updating card info on itunes
If your credit card number has changed, you can’t change the card number on the screen where you edit the card details.
Apple’s App store required your Bank card data for online purchase in your i Phone, i Pad and i Pod touch, Also from Mac.
If the day comes when you no longer have control of the email address that is your Apple ID, you'll need to change it.
Before you change your email address, it is important that you sign out of every other Apple device and service that uses your current Apple ID.
Changing your email address is trickier because it is your Apple ID.
If a credit card in your Google billing account is about to expire, you should update the card's expiration date in your Admin console.
If the card’s CVC number changes, you should update that as well.
If your current Apple ID uses an email address that ends in @me.com, @or @mac.com, you might not be able to change your email address and the Change Email Address field will not be visible.
Enter your Apple ID password when prompted to do so.
Here I explained steps on update/ Edit/ remove or Delete old data in a secure way from your i OS devices or Mac.