https://support.apple.com/en-gb/HT201389
Change your Apple ID country or region
Before updating your location, you must spend your store credit, cancel your subscriptions and get a payment method for your new country or region.
What to do before you change your country or region
- Spend any remaining balance in your Apple ID. If you’re not sure whether you have a balance, check your Apple Account balance.
- Cancel your subscriptions and wait until the end of the subscription period.
- Wait for any memberships, pre-orders, film rentals or Season Passes to end, and wait for any pending store credit refunds to be processed. You can cancel a pre-order.
- Make sure you have a valid payment method for your new country or region. See which payment methods you can use.
- Re-download your apps, music, films, TV programmes and books on any devices you might use to play or read them in the future. Some types of content may not be available in your new country or region. Find out what types of content and service are available in your new country or region.
Use your iPhone or iPad to change your region
- Open the Settings app.
- Tap your name, then tap Media & Purchases.
- Tap View Account. You may be asked to sign in.
- Tap Country/Region.
- Tap Change Country or Region.
- Tap your new country or region, then review the terms and conditions.
- Tap Agree in the top right-hand corner, then tap Agree again to confirm.
- Select a payment method and enter your new payment information and billing address, then tap Next. You must enter a valid payment method for your new country or region.*