There are two ways to unbind a credit card from your iTunes account:

1. If your account was a free account when you applied for it and was later changed to a paid account, you can change it directly in the account Just leave the payment information as None.

2. If your account was paid when registering, it is recommended to log in to www.apple.com.cn/support/itunes and select the "Contact Support" page to contact the iTunes Store support team to cancel the credit card binding.