Since the country in the account cannot be changed (when invoices are paid), a client can do this.
Create a New Account
The recommended solution is to create a new account with:
the correct new country
updated billing information
However, a client must have a document copy that confirms the new residency.
Furthermore, the used email address cannot be used for multiple accounts.
Transfer the Services to the New Account
Once the new account is created, you can request to transfer the services to the new account by following this guide.
When services are transferred, the old account will be closed.