How do I do a second tax return with turbo tax

You have to set up a separate account if you want to file another return using TurboTax Online. You will need to create a completely separate login for that person.

TurboTax has a download product that includes up to 5 federal filings. Here's the link to that:

https://turbotax.intuit.com/personal-taxes/cd-download/

Online is only good for 1 return.  But you can use the same email address for 5 accounts.   How to start another return in the Online version https://ttlc.intuit.com/replies/3288574