As long as you haven't mailed your return (and you plan to file by mail), you can use the instructions in the TurboTax FAQ below to re-open your return to make changes.
https://ttlc.intuit.com/replies/7306547
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
