No, if you live in DC and your only source of MD income is wages, you will only need to file a DC resident state income tax return to report all income from all sources (including your MD wage income).
DC has what is called a state reciprocal agreement related to wages with MD. This allows nonresidents to not have state withholding taxes taken out for wages earned in these states.
You can get rid of a state without clearing your federal return by just deleting the state from your list of states under the "State Taxes" tab.
Please note that you will not have a delete option until you actually start working on the state. Select that you want to start the state return under the state taxes tab. The system will start calculating. Then go back into the state tab at the top of the screen and you should now get a choice for that state to either continue or delete. You won't be charged for just starting the state return. You would only be charged (if applicable) when you are getting ready to file.