(this is only my 2nd year filing taxes in the US)
If you don't need all of the features of TurboTax Deluxe, you can downgrade from TurboTax Deluxe to the Federal Free version of TurboTax Online, as long as you haven't paid yet (or registered in a free version) - but please bear in mind that you will need to clear any data which you have entered, and start over in the other TurboTax version. This is the only available method to switch versions.
Please see the following TurboTax FAQ, "Can I switch to a lower-priced version of TurboTax Online?":