Level 15

After you file

Nothing was sent to the IRS after your original (unchanged) tax return was filed.

Remove any changes you made.  Wait for the IRS to process your tax return and send your tax refund (if applicable).

Then you can change the 2017 tax return using the amend process.  An amended tax return, Form 1040X, can only be printed and mailed by you to the IRS, it cannot be e-filed.

See this TurboTax support FAQ for amending a tax return -