I signed in to TurboTax with a license code. Now I need to delete the return and start over. Is this possible?

Seems like you are posting from the Online web version and not the Desktop program installed on your computer.  Get out of online and run the program.  It should have a blue menu bar across the top.  Then go up to File- New.  If you have a black menu bar down the left side that is the Online version.  

Did you get the Desktop program installed and activated with the License Code?   How to install with a License Code

https://ttlc.intuit.com/community/tax-topics/help/activating-turbotax-cd-download-software/00/852971

I am assuming you purchased the turbo tax software either online or at a store and received a license code.  If that is the case, the code is generally only need to download and install the software on your computer.  You shouldn't need to enter it for every return instance you create.  If the software isn't asking for a code, keep going.