You did start a New Tax Return for your brother by clicking on the File menu at the top left of the program screen and then click on New Tax Return, correct?

In the Personal Info section when entering his information you should have selected Ohio as his resident state.  You should also have indicated that he did Not live in any other states and that he did Not earn any money in any other states (if that is accurate).  If that is how you entered his information then the only state tax return would be for Ohio.

Check his information in the Personal Info section of the program, is it correct?

Ohio was selected as his state of residence and "Other State Income" says "None." 

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@KevinPeshick wrote:

Ohio was selected as his state of residence and "Other State Income" says "None." 

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Try removing the unwanted state from his tax return using the procedure in this TurboTax support FAQ - https://ttlc.intuit.com/community/state-taxes/help/how-do-i-clear-my-state-return-in-the-turbotax-fo...