How do I delete or disable a combined tax rate? Once I made it it was uneditable and I can't find a way to edit or disable it as it isn't doing what I need it to do.

I have a way where you can make the sales tax rate inactive, david217.

Before doing so, please take note that making a sales tax rate inactive doesn't delete it completely.

Here's how:

1. On the left panel, go to Taxes.
2. Select Edit VAT or Edit GST, then choose Edit Rates from the drop-down list.
3. Find the tax rate you want to deactivate, then switch it from On to Off.
4. Click Yes to confirm.

I've got this article for more details: Remove a VAT or GST rate.

Please let me know if you have any additional questions about sales tax or other concerns with QuickBooks Online. Thanks.