Not sure how this was mistaken as traditional versus roth. What can I do to fix 2017 return? Do I need to do this before filing this year and do a backdoor this year before April 18th?
To confirm, you made a Roth IRA contribution for 2017 and your MAGI allowed you to make a Roth IRA contribution (see 2017 Pub 590a page 40) but you entered it as a nondeductible traditional IRA contribution and therefore TurboTax created Form 8606.
If this is correct then all you need to do is correct the 2017 Form 8606 (showing that you don't have a basis). You don't need to do a backdoor if the funds were never in the traditional IRA account.
If you weren't allowed to make the Roth IRA contributions because of your MAGI then you would have to pay the 6% penalty for each year the excess stayed in the account, starting in 2017 until you remove the excess contribution. You can request a regular distribution (without earnings) to remove the excess after the due date of the return.