You will have to amend your 2019 return and correct the error in the questions you answered.
Your child must a Qualifying Child for you to claim Head of Household. 2 The term qualifying child is defined under Dependents Table 4 Pub 501
Below are the questions you are asked to determine dependency and other child related benefits.
The screens can be tricky. Basically, if the question applies to residence, it pertains to Head of Household, Child Care and EIC. If the question is about claiming the child, it has to do with dependency. This is mainly used when two divorced parents are splitting benefits, but the questions are the same for anyone.
Dependency Questions/Non-custodial parent
What's Megan's relationship to you?
We know Megan is_, but we have to ask: Did she pay for most of her living expenses?
Do you have an agreement with Megan's other parent about who can claim her?
Is Megan's other parent claiming Megan per your legal agreement?
Are you letting Megan's other parent claim Megan for 2020?
Head of Household Questions/Custodial parent
What's Megan's relationship to you?
How many months did Megan live with you in 2020?
Where did Megan spend the most nights in 2020?
Did a relative live in your home and help support Megan?
