Hello and welcome to Apple Support Communities, Sinscere!
I understand you've accidentally switched over from Russian to US iTunes & App Store. I see you've tried switching back, but you're being asked to cancel your Apple Music subscription. I'd be happy to provide information to help you address this.
It looks like you've followed the steps outlined here: Change your Apple ID country or region
"What to do before you change your country or region
- Spend any store credit remaining on your Apple ID. Learn what to do if your remaining store credit is less than the cost of a single item.
- Cancel any subscriptions, including Apple Music, 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.
- Make sure that you have a payment method for your new country or region.
- Redownload your apps, music, movies, TV shows, and books on any devices that you might use to play or read them in the future. That's because 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.)"
Since it's requiring you to cancel Apple Music but you do not see the option, it looks like you've already canceled it. Once you've canceled it, you need to wait for the subscription period to end. Based on your image, it looks like yours ends 13 December 2019. At that point, you should be able to switch back to Russia.
Have a great day!