If you need to make a change or correction to your return after it's been submitted and accepted, you can submit updates by amending your return with Form 1040X. You usually have three years from the date you filed your original return to submit the amended return (click for more information)
This link will bring you to specific amend instructions for each tax year and version of TurboTax.
Note: Form 1040X cannot be e-filed, meaning any changes you make will not be recognized by the government unless printed and mailed. TurboTax will tell you which forms to send and where to send them.