My return is complete. How do I start a new return for someone else?

[JamesG1]

TurboTax Online restricts users to one federal tax return per account (user ID) per year. Using the same account for a second return will overwrite the first, causing it to be lost forever. 

To file multiple returns online, you must create a separate, unique account for each person, though you can use the same email address for up to five accounts. 

See this TurboTax Help.