I was prompted to use Premier for $39.99 which I accepted. I have not submitted. I now think the Standard version was perhaps sufficient. How can I backtrack to Standard?

Unfortunately, there is no way to downgrade or remove extra features from a TurboTax return. You would need to create a new return to go down to a different product.

To start a new return, select “Start a New Return” from under “My Accounts & Returns”. Once you have started your new return, you can select “View All Returns” from under “My Accounts & Returns”, and delete the unwanted return by clicking the small Trash Can next to it.