Cant change my AppStore region

To change your region you must fulfill certain requirements

• 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.

if you did not fulfill all of these requirements, you cannot change your region.

Change your Apple ID country or region – Apple Support (UK)