You don't need to start over to change filing status to head of household if you qualify. Just go to Personal Info and change the filing status. If you have a dependent that qualifies you as head of household, you should have already entered the information on that dependent.
Head of Household filing status qualifications:
1. You are not married or “considered unmarried” on the last day of the year. You are considered unmarried if you lived apart from your spouse the entire last 6 months of the year.
2. If "considered unmarried" you file a separate return from your spouse.
3. You paid more than half the cost of keeping up your home for the year.
4. You have a qualifying child (whether or not you claim the dependency exemption) or you claim a dependency exemption for a “qualifying person” who is related to you and who lived with you in the home for more than half the year. An exception is a parent does not have to live with you to be a qualifying person.