In most cases canceled debt is additional income. You have to report it as income and pay tax on it. There are a few exceptions, which you can read about in IRS Publication 17, at the following link.
https://www.irs.gov/publications/p17#en_US_2018_publink1000171963
Are your 1099-Cs for 2018 or 2019? If they are for 2018, and your situation does not meet one of the exceptions, you will have to file an amended return (Form 1040X) to add the income to your 2018 tax return. If they are for 2019, they will go on your 2019 tax return.
Go to the following link for instructions to amend a 2018 tax return that you filed with TurboTax Online.
https://ttlc.intuit.com/questions/4667226-how-do-i-amend-my-2018-turbotax-online-return
An amended return has to be filed on a special form, Form 1040X. It cannot be e-filed. You have to print it, sign it, and file it by mail. It takes the IRS up to 16 weeks to process an amended return.
Don't file the amended return until your first return has been accepted and you have received the original refund.