Trying to change my payment method in order to purchase more iCloud storage

Hi Yasir2019,

Welcome to the Apple (user-touser) Community

If you have active subscriptions:

you will need to keep at least one payment method in your account at all times,

so you may need to add new payment methods before deleting older ones.

To see what payment methods Apple can accept in your country or region:

Payment methods that you can use with your Apple ID - Apple Support

How to change an Apple ID Payment method:

What to do: If you need to change or update your Apple ID payment method – Apple Support

How to Add an Apple ID Payment method:

Add a payment method to your Apple ID - Apple Support

How to delete an Apple ID Payment method:

Remove a payment method from your Apple ID - Apple Support

All the best :-)