How do I clear my App Store balance

If your balance is less than the cost of a store item, then Contact Apple Support and have them zero your balance for you. You can also purchase something for more than your balance and the remainder will be billed to your payment method on file.

Also, we are not Apple and cannot zero your balance for you, we are merely just a user-to-user forum.

⇢ Change your Apple Account country or region - Apple Support