If you have already filed the 2019 tax return then that return cannot be canceled or retrieved.
If you have not filed the 2019 tax return then clear the return and start over.
If you have not paid for the online edition you are using, have not filed your tax return or registered the Free edition, then you can clear your return and start over. Click on Tax Tools on the left side of the program screen while working on the 2019 online tax return. Click on Clear & Start Over.