What if I accidentally filed as head of household but am single? How do I resolve this?

You can qualify for Head of Household if you are Single and have a dependent.  Turbo Tax wouldn't let you select Head of Household if you don't qualify.  

@jacquelineconn - amend the tax return and pay back the money as reflected on the amendment.  who did you claim as a dependent that you are now wanting to remove? what were the circumstances? 

Well, how did you manage to file as Head of Household if you did not claim a qualified dependent?   The software will not offer HOH as a filing status unless you claim a blood-related dependent.

Am I Head of Household?

https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household

https://ttlc.intuit.com/questions/2900097-what-is-a-qualifying-person-for-head-of-household

If you qualify as Head of Household, when you enter your marital status (single or married filing separately) into MyInfo, and then enter your qualifying dependent, TurboTax will offer HOH as your filing status.