How to delete my debit card off my app ?

You need to have a payment method on file, even if the app you want to download is free.

If you want to delete your card, you need to add another payment method.

If you want to change your card, see -> Change, add or remove Apple ID payment methods

Add a payment method to your Apple ID – Apple Support (UK)

• add first the new card, then remove the old one.

See also -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

You can also use your Apple ID balance as payment method: Add money to your Apple ID balance

Add money to your Apple ID balance – Apple Support (UK)

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

imelda264 wrote:

my debit card is charge for a subscription how can I delete my debit card on the account

You can’t delete your debit card, but you can cancel the subscription→If you want to cancel a subscription from Apple - Apple Support

All you have to do is go to the wallet app or to your account setting either in the settings section or on the ID settings on the website and click change payment method