If you have already started your TurboTax Online
return, then there is no way to get back to that option. You would need to
start a new return.
If you are starting a new return, here is how to
transfer information (personal details, carry forward amounts, etc.) from your
previous year's tax return in In TurboTax Online:
https://turbotax.community.intuit.ca/replies/2647786