The 2018 comparative information shown with my 2019 Tax Return is incorrect (didn't end up filing with TurboTax Premier), can I delete it?

No, there isn't a way to delete the 2018 information from the summary.

There are only a few things on the 2018 tax return that affect your 2019 tax return. The comparison is informational and designed to help you identify things you have missed.

If you have capital loss carryovers from 2018, you will need to correct that. 

1. Use the search box toward the upper right corner to search for Capital loss carryover.
2. Click on Jump to Capital loss carryover.
3. Enter the information from the return that you filed.

If you have a taxable state refund, you will need to review that section to make sure it matches the 2018 tax return that you filed.

If you have a business or rental with any depreciation, you will need to review the depreciation carefully to see if there are any changes.

If you paid AMT in 2018 and you think you may have an AMT credit, be sure to complete the AMT credit using your  information from the return that you filed. 

If you had an NOL, passive activity loss carryover or any other carryover, you will need to review those sections carefully.