How can I cancel my TurboTax return if I already e-file, I want the professional to do my text return for me.
It doesn't look like you can. Before you hit the button to submit, it very clearly said that you cannot undo the transmission and likened it to "dropping the return in the mailbox."
You have clicked a link to a site outside of the TurboTax Community. By clicking "Continue", you will leave the Community and be taken to that site instead.