I need help to empty App Store credit.

See this for help.

Change your Apple ID country or region - Apple Support

This is the section that will most likely apply to you. I copied it from the support page for which I posted the link above.

If you can't change your country or region

• If you can't change your country or region, make sure that you canceled your subscriptions and spent your store credit. Complete these steps before you try to change your country or region.
• If you're a part of a Family Sharing group, you might not be able to change your country or region. Learn how to leave a Family Sharing group.
• If you still can't change your country or region, or you have less store credit than the cost of a single item, contact Apple Support.