TurboTax does not support IRS Form 982, Reduction of Tax Attributes Due to Discharge of Indebtedness (and Section 1082 Basis Adjustment).
You will have to complete the form manually and then print the form to be included with your mailed federal amended tax return. The amended return cannot be e-filed if you are attaching Form 982.
Go to this IRS website for Form 982 - https://www.irs.gov/forms-pubs/about-form-982