As long as you haven't gone far enough into the program that you registered or paid any fees, then you should be able to clear and start over. Follow these steps (if you are using a mobile device to log in and the below steps don't work, try this on a computer)-
If you cannot clear and start over because you have already registered the product, then you will have to create a new account. You can make a new account with your same email address but a different username. You might want to click out of all browsers and restart computer to make sure you don't get logged back into your old account. The information from your old account will get cleared out automatically at the end of the tax season.
As long as you haven't gone far enough into the program that you registered or paid any fees, then you should be able to clear and start over. Follow these steps (if you are using a mobile device to log in and the below steps don't work, try this on a computer)-
If you cannot clear and start over because you have already registered the product, then you will have to create a new account. You can make a new account with your same email address but a different username. You might want to click out of all browsers and restart computer to make sure you don't get logged back into your old account. The information from your old account will get cleared out automatically at the end of the tax season.
See this Turbo Tax FAQ on how you can Clear and start over.