Hello! Thank you for using Apple Support Community.
If you are trying to zero your balance and still have a valid credit or debit card, you may purchase an item from the App or iTunes Stores for more than your balance. The remainder will be billed to your card, leaving you with nothing in your account balance.
Alternatively, you could ask Apple Support to remove and keep the balance. Remember that the people on this forum are just other Apple products users like yourself and are unable to do this for you. Use this link Apple provides to take you directly to the managing and editing an Apple ID people who will do this for you --> https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0998&symptom_id=20198
This is more direct than using Official Apple Support which will just eventually lead you there after some searching.
If the above direct link does not work for you, go to https://getsupport.apple.com/?s=n , enter “empty balance” or “zero balance” in the search line, press enter to search, then on the next page select “Clear Apple ID balance”. On the next page select a chat or telephone call option.
Alternatively give Apple a phone call. Find a list of telephone numbers at:
Contact Apple for support and service - Apple Support
If you are asking about this because you are changing regions, take a look at this article:
Change your Apple ID country or region - Apple Support
Have a great day!
P.S. Others may suggest you use the general support link at Official Apple Support but the above methods are more direct ways of getting in touch with the right people at Apple. Use one of the above links and save time and trouble.