How do I remove a credit card from the payment method?

Tap Settings > iTunes & App Stores > Apple ID: > View Apple ID > Payment Information > None

thanks but i have tried I can't see none there!

Why can't I select None when I edit my payment information?

When you try to edit your payment information in the iTunes Store, App Store, iBooks Store, or Mac App Store, you may see these symptoms:

• When you try to remove the payment information from your account, the None option is hidden.
• When you create a new store account, you're asked to enter a credit card and can't select None.
• When you sign in to the store, you must verify your payment information and enter a credit card to save your payment information.
• When you change the country or region of an existing Apple ID, you're asked to enter a credit card and can't select None.

Resolution

If you want to select None and remove the payment information or credit card from your account, follow these steps.

Using an existing iTunes Store or App Store account

If you have an unpaid balance or payment due, you can't select None as your payment type. To see which order you need to pay for, view your purchase history. When you sign in to the store, you may see a message that there was a billing issue with your last order. Click the Billing Info button to see the order.

After you pay for the order, you can change your payment information to None.