As long as you have not actually filed (haven't mailed or successfully efiled), here's how to open the return back up to change filing methods if TurboTax thinks you are finished:
NOTE: Do NOT use this method to open a return to make changes/edits to an already-filed return (one that has actually been mailed or efiled.) If you later need to make changes to an already-filed return, you have to go through the formal amending process, and your return must start off exactly as originally filed.
As long as you have not actually filed (haven't mailed or successfully efiled), here's how to open the return back up to change filing methods if TurboTax thinks you are finished:
NOTE: Do NOT use this method to open a return to make changes/edits to an already-filed return (one that has actually been mailed or efiled.) If you later need to make changes to an already-filed return, you have to go through the formal amending process, and your return must start off exactly as originally filed.