This question has come up before and Roku has never reported a way to transfer an account between regions. All you can do is create a NEW account in your new location and link your Roku to that.
To link to a new account, you'll have to do a factory reset on your Roku and set it up all over again.
(Settings > System > Advanced system settings > Factory reset)
When you set up the Roku after doing the Factory reset, be sure you are connected to the internet via an IP located in your new area (not via a VPN with its server elsewhere). Link your Roku to a new Roku account in your new region. And just to be sure, it's a good idea to identify the account with an email address also located there.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X