Select whether to subscribe now or use a 30-day free trial and the type of subscription you will be using.
Click Add another company, then enter your existing Intuit login credentials.
Follow the on-screen instructions to set up the account.
After that, you can now import your customer, suppliers, chart of accounts, and products and services list from the old account. This article will guide you to import them in: Move your lists to QuickBooks Online.
Lastly, you can cancel the account once everything is set up on your new account.
Let me know in the comment section if you need further assistance. I'd be happy to answer them for you. Take care.