In short, you will need to re-enter the information into the TurboTax Business product; there is no way to "convert" a Schedule C business (filed with a TurboTax individual tax preparation product) to an S corporation 1120-S return (which is prepared and filed using TurboTax Business).
You can, of course, re-enter the information from your Schedule C (and related worksheets) into the Business product but there is no easy method of actually converting that information.
I will page @Rick19744 for further input.
