It depends upon the type of income that you designated as QBI income.
Go back to that section of TurboTax (under the Income & Expenses tab) and scroll down to select to edit/review that income section that needs to be changed. You will need to go through all the screens for that income until you come to one that asks for either:
1) If a rental property, then "Do you want to use a safe harbor to qualify for a deduction?" On this screen and the next are where you would change your answers to remove the QBI deduction.
2) If a self employed business, then to the screen "How much of your WORK took place within the United States?" This screen and the next few all relate to the QBI deduction.