If your returns have already been filed you will have to file an amendment. Amendments are filed on form 1040X and must be mailed in and cannot be Efiled.
Please see the link below. This will guide you on how to file an amendment.
Please note: Form 1040X will not be available until 2/7/19.
https://turbotax.intuit.com/tax-tips/amend-return/how-to-file-an-amended-return-with-the-irs/L6kO691...
