To empty your balance, add an external payment method (e.g., a card) to buy an item (not a subscription) priced more than your balance. The difference owed will be billed to your card, leaving nothing in your account. Review:
- Payment types you can use —> Payment methods that you can use with your Apple Account - Apple Support
- How to add a payment type —> Add a payment method to your Apple Account - Apple Support
Another way is to ask Apple to remove and retain the balance. The people responding here are Apple product customers like yourself and cannot do this for you. Contact methods:
- Click on the special empty-balance-request chat link at the bottom of this support article ➔ Check your Apple Account balance - Apple Support
- General Apple support and service contact ➔ Contact Apple Support - Apple Support If live support options are available they will show near the bottom left. If numbers show as colored links, click on them for more options.
- With an iPhone, iPad, or Vision, you may be able to chat using the Apple Support App if it is available in your country ➔ https://apps.apple.com/app/apple-support/id1130498044
If you cannot contact Apple then the first method is the only way to empty your balance. If neither method works then you will have to create a new Apple Account when you are in the new country.
Additional changing-account-region support article ➔ Change your Apple Account country or region - Apple Support