The Clear & Start Over link is most certainly available when using the TurboTax online editions.
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 with a lower priced edition. Click on Tax Tools on the left side of the program screen while working on the 2018 online tax return. Click on Clear & Start Over.
If you do not see any links on the left side of the online program screen, then click on the 3 horizontal bars at the top left of the online program screen to open the left side column.
