You're mixing up School district (SD) and City Income tax. They are two different types of income taxes. You do not live in a SD with a tax ( neither Columbus CSD-2503 or Dublin CSD-2513 are taxing districts). You should not be filing an SD return (form SD100). Go back thru the SD interview. You'll reach a screen where you can exclude the SD return you prepared.
Instead, you should be filing a Dublin City return. That can't be done in TurboTax. See http://dublinohiousa.gov/taxation/. Dublin is one of the few cities providing a 100% credit rate for tax paid to other cities (up to the 2% rate).
However, the statement "so all of my local tax (2.5% for Columbus) goes to Columbus" would seem to indicate that you do work in a city with an income tax (Columbus). I assume that means your employer shows withholding in box 19 of your W-2 and COL (or some other code for Columbus city, not SD) in box 20
