If you haven't filed yet, then log in and click Take Me to My return. Then edit your W2 by searching for “W2” in the search box in the top right hand corner and clicking the “jump to W2” link. Click Edit next to the W2 in question and scroll down towards box 13 (see screenshot). If the statutory employee box is checked on TurboTax, but not on your actual W2, then uncheck the box. After you uncheck the box, finish the remaining W2 screens.
If you have filed, then use the amendment process to accomplish the same result. Use the link below to get that started and during this process you will get to a screen with a list of items you can change - W2 will be the very first section.