If you click live assistant by error is it true that Turbotax won't allow you to delete the service/extra charge even of it was not used and not needed. Is this a scam?

Unfortunately, once you have upgraded or added features to your TurboTax return, there is no way to downgrade or remove the extra features. You would need to create a new return to go back to the original product. 

To start a new return, select “Start a New Return” from under “My Returns” in the bottom left corner. Once you have started your new return, you can select “View All Returns” from under “My Returns”. Then delete the unwanted return by clicking the small Trash Can next to it or “Delete” under the return’s name.