If you already started a state return, you can delete it as long as you haven't paid for it yet (or registered your free version with the state attached).
If you plan to eventually file a state return, just not right now, you can skip it and file only your federal return. However, if you wish to e-file your state, you'll be able to do so only after your e-filed federal return has been accepted. More info
Here is how to delete your state return in TurboTax Online: https://ttlc.intuit.com/replies/3301384