Since you previously filed a 1065 form for your LLC business taxes and now need to file a 1120S form, you will want to start a new tax return in TurboTax Business and do not opt to transfer in your return from last year (select you will continue without transferring). This will allow you to set up the business return as one for an SCorp. Therefore, you will have some set up entry to do since it will be like entering a new business, but you will be able to create the 1120S form.
The 1065 and 1120S forms are programmed completely differently so there is not a way to transfer previous years data from one form type to another.
