How do I remove the automatic calculation of sales tax on my invoice

We'll have to select the Turn off sales tax option to remove the automatic calculation of sales tax on the invoices, adeslat. I'll guide you through the steps to ensure everything goes smoothly for you.
 

To start, print or download your Balance Sheet report before deleting any transactions. This helps you accurately re-enter transactions.
 

Next, run the Sales Tax Liability report and customize it to see the transaction report. Here's how:
 

1. Head to the Reports menu on the left panel in your company.
2. In the Find report by name field, enter Sales Tax Liability report.
3. Click the Report period ▼ dropdown to select All Dates and Run report.
4. In the Taxable Amount column, click the amount to view the transaction report. 
5. This action will show all transactions that have sales tax.
6. In the Transaction Type column, select the entry.
7. Take note of the transaction details and then delete them.
    

Now, let's disable the automated sales tax option. Refer to this article for detailed instructions: Turn off sales tax in QuickBooks Online. Proceed directly to the Turn off sales tax in the automated sales tax experience section.
 

After turning off the sales tax function, let's re-enter the deleted transactions using the Audit log. You can also batch upload multiple invoices at once.
 

You might also want to look into QuickBooks Live Expert Assisted to get personalized support managing your accounting tasks. They'll help automate bookkeeping processes, making it easier to manage tasks such as invoicing, expense tracking, and sales tax management. 
 

Feel free to visit the Community again if you need further assistance navigating around QBO or have other product-related concerns or questions. We're always ready to help you out.