Do not click on anything that says "amend" if you have not e-filed. Amend is only used to make corrections to a return that has been filed and fully processed. If you need to make changes to the return before you e-file it, you can get back in by clicking "add a state". You do not really have to add a state return, but that trick will get you back in to the software to make changes.
As for starting over---You can clear and start over if you have not registered, paid, or e-filed. If you have done any of those things it is too late to clear it but you can make changes via the interview screens.
CLEAR AND START OVER
You do not need to amend if the original was never filed.
If the return was not mailed, you can continue with the same return by selecting "Add A State" and adjusting the original return.
HERE is an answer thread including steps for when the return is for a prior year.