To change a tax return that has already been filed, you must prepare, print and mail an amended return form 1040X. DO NOT change your original tax return until you start the amended return. If you have already changed it from the way it was originally filed and accepted, you must change it back before you start the amended return. Wait until you receive the refund from your original return before beginning your amended return to make sure you enter the correct amount. Here is an FAQ to help you:
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
An amended return cannot be efiled. You must print and mail it yourself. TurboTax does not print and mail it for you. In normal times, it takes the IRS about 16 weeks to process an amended return. It's taking even longer now since the IRS is currently not processing any mailed returns.