I'm trying to clear my return and start over at a later time. It states it can not clear because I'm registered. What does that mean?

In TurboTax Online, you can't Clear & Start Over after you've registered. This most likely due to having a paid version of TurboTax.

If it's convenient, consider opening a new account under a new username. Up to 5 accounts can be tied to the same email address.