How do I delete a "filed" (printed but not filed) return, so that I can go back and make changes or start over?

By choosing the Print and Mail option, turbotax 'thinks' that the return is completed, but if you don't mail it then it is not submitted and you can make changes.

On the Tax Home page, under Your tax returns & documents, click "Add a State".

This allows you to edit the return by clicking the Federal or State option on the left hand side.

Since turbotax 'thinks' the return was mailed, under Tax Tools, "Clear and Start Over" will NOT work.

You will have to make changes and re-print the tax return to mail in. It is likely that turbotax will not let you e-file.

In order to completely clear and start over to be able to e-file, you would need to create a new account with a different email address.

-This info was provided by turbotax customer support to me, the one who was impatient in clicking through the return to see the printed forms to check for errors, then got locked out of the return.