If you are using the Desktop version you can delete the return you don't want, start the program, under the Continue box on the first screen click on the blue link Find a Tax File, you will see a list of your returns, right click on the one you don't want & choose Delete.
OR, The default location for the TurboTax files is the TurboTax directory off of Documents (or sometimes they are in the Documents directory), you can delete a tax file from there, right click on the return and choose Delete.
