I need to cancel before I finalize my taxes on here I've used this software twice with different outcome one other with outcome different have an appointment with IRS

As long as you have not filed your return you are free to use another tax service. The return you are currently working on can be cleared out. If you have not submitted or registered your return you can delete it using the following steps.

1. Sign into your account and select your current return

2. Select TaxTools  on the bottom left and then clear and start over

This will clear out all of the information that you have entered.

It says I can't since I already registered? I never finalized my return... decided to get an appointment with the IRS here

You cannot clear your return if you have already registered it, but your information will not be filed.