How can I delete my credit card details

Is this for your Apple id? If so, follow the directions in this article: Change or remove your Apple ID payment information - Apple Support

-AJ

There are a few way of changing your payment method. But I don't believe you can Delete you number completely off your system. But lets start with a iOS device.

1. Go to setting
2. Go to the iTunes & App Store.
3. Press on your Apple ID located on the top.
4. Enter your Apple ID Password.
5. Then go to payment methods. There you will find the options to change you Payment options.

Now if you are running on a Mac or PC computer these steps will help you change your information.

1. Open the iTunes Program / App
2. On the upper right you will see your Apple ID or Name next to the search bar.
3. click on your name and go to Account Info.
4. Enter your Apple ID password.
5. You should be about to see your Payment method and the option to change it.

This should be able to help you out on changing or removing the current card you have on file with your account.

This is a more visual list that I just gave you.

Change or remove your Apple ID payment information - Apple Support