If you have already e-filed and been accepted by the IRS, you cannot change the status because your tax return has already been electronically sent to the IRS. You would wait until after you have received your tax refund and then Amend your tax return using Form 1040X. Amending instructions will be available - in late January or early February 2018.
If the IRS rejects your tax return, they will send it back to your TurboTax account to make the corrections that caused the rejections and you can also change your filing status to single.
