Do I need to file an amended return if I showed a Non-passive K1 as a NOL. I just need to back out the loss. I owe zero taxes with and without this loss.

you may file amended Sch K-1. Start with the Sch K-1 form for the appropriate year and check the "Amended K-1" box at the top of the form. Each Sch K-1 has some variable information, including the codes used. Use the Sch K-1 instructions to locate the necessary codes for the completion of the amended Sch K-1. Attach all necessary amended Sch K-1 forms to the Form 1120S. you may send a copy of any amended Sch K-1 form to the shareholder as well as to the IRS.