I want to change region and I still have 0.4$ that I can’t make purchase with

If you want to change Country or Region, you must comply with all regulations described here ->  Change your Apple ID country or region

Change your Apple ID country or region - Apple Support (KW)

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What to do before you change your country or region

• Spend any balance remaining on 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, movie rentals, or Season Passes to complete, and wait for any pending store credit refunds to process. You can cancel a pre-order.
• Make sure that you have a payment method for your new country or region. See what payment methods you can use.
• Redownload your apps, music, movies, TV shows, and books on any devices that you might use to play or read them in the future. Some types of content might not be available in your new country or region. Learn what types of content and services are available in your new country or region.

but I to cancel 0.4$ I have how do I cancel it

1.

👉 If your balance is less than the cost of a single item, contact Apple Support directly, they will help you clear your balance: Get Support

2.

You need to Cancel your subscriptions and wait until the end of the subscription period. 

3.

Make sure that you have a payment method for your new country or region. See what payment methods you can use.

You need to have a debit / credit card issued by a bank in your new country.

You need to have a billing address in your new country.

Buy something more expensive than your balance and use a different payment method for the excess amount; if you can't, use this link to ask the iTunes Store staff to zero it.

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