It seems that you have the QuickBooks Online US account, which is why it requires a US phone number. You'll want to create an account specific for Hong Kong so you can update the billing information. You can sign up here, https://quickbooks.intuit.com/hk/.
Before you cancel the other account, you'll need to export the reports and lists:
Click the Gear icon.
Select Export Data.
On the Reports tab, set the desired date range.
Add or remove items from the Reports and Lists tabs by toggling the slider.