Hi Mandy,

In QuickBooks Online once we turned on the VAT feature, there will be no option to turn this off.

As a workaround since your client isn’t VAT registered, we can help him to set the default tax rate selection to choose Out of Scope of Tax or No VAT for all their future transactions. 

Here’s how:

1. Click the Gear icon.
2. Click Accounts and Settings.
3. Click Advanced.
4. Go to Accounting.
5. Click the drop-down in Default tax rate selection and choose Out of Scope of Tax (or No VAT.)

The Out of Scope of Tax is used for none vat registered business. This means, if you use it then it will not show in any taxes reports in your account. 

Stay in touch, and have a great day!