You will have to download the TurboTax software for 2017, you won't be able to use the online version. Once you are done with the return you will have to print and mail the return. Please see this FAQ for more information:
https://ttlc.intuit.com/replies/3301770
To clear your 2018 return please see this FAQ:
https://ttlc.intuit.com/replies/4248526
