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 e-filed.
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...