How to eliminate an erroneous 1040-X before filing taxes

I'm trying to help out a friend who made an error completing their taxes online.

They had completed their 1040, but have not filed it yet. Nothing has been filed.

 

They were receiving a refund.

We realized (before filing) that it would be best to apply their refund to next years taxes.

However, instead of going back and updating TurboTax accordingly, they erroneously created a 1040-X.

The 1040-X of course should not be filed, since the 1040 hasn't been filed yet.

 

I'm more used to the TT download product, and haven't used the online version before.

Since TT thinks we're done (even though we haven't filed), I'm not seeing a way to get back into the dialog again so I can properly tell it to apply the refund to next years taxes (and somehow delete the 1040-X). How can I re-open the return and update it before filing?