Thank you for your question!

Once you log in to your CRA My Account with your user ID and password, you are directed to a page titled CRA Login and Security Options. From there, click on the Change CRA User ID link. On the following page, there is a field to enter your new user ID. Create your new user ID, and make sure it complies with the user ID checklist. Enter your current password. Clicking Next takes you to another screen to confirm the change. If your new user ID is not structured to comply with the user ID checklist, you must enter a new one, and then click Next again.

Please visit Canada Revenue Agency to register for a CRA My Account.

Our TurboTax article will help you learn more about Registering for your CRA My Account 

Thank you for choosing Turbotax.