If you decide not to file with TurboTax, and your return has not been received by the IRS or Rejected, you would simply log out of your account and not continue. If you want to remove any information, you can click on the "Federal" tab located in your Menu Bar on the left side of your screen and go back into any area to delete entries.
If you need assistance with any issues or rejections, and you decide to continue to file with TurboTax, please start a new thread posting the issue.