Read this link for information about general requirements for changing store country:
Change your Apple ID country or region - Apple Support - Apple Support - https://support.apple.com/HT204447
To remove balance:
Option #1:
The above link used to have this information but now no longer exists in this form. - "If your store credit is less than the cost of a single item on the iTunes Store, App Store, or iBooks Store, you can add a credit card to your account [https://support.apple.com/HT201266]. When you buy an item, you will use the remaining store credit and charge the remainder of the purchase to your credit card."
Option #2:
"If you don't have a credit card, contact iTunes Store support." Apple will remove the balance and keep it.
Click here --> https://support.apple.com/choose-country-region/media-services Select an option and keep on working your way down the menu until you get to one saying your "topic isn't listed". This will present you with support by chat or telephone call.
Option #3
I haven't heard of anybody trying this but: Create and add money to an iTunes Pass - https://support.apple.com/HT203021 - "With an iTunes Pass, you can add funds to your iTunes account at Apple Stores or select retailers. You can use the funds to buy music, apps, movies, books, or TV shows*." Limited countries only. Add exactly what you need to buy something (don't forget tax, if applicable).
