Can I file taxes a a single even though the W4 is head of house hold

Your W-4 was given to your employer to tell them how much tax to withhold from your paychecks.  It did not go to the IRS.  Your W-4 does not dictate how you have to file your tax return.  If your filing status is Single, then that is what you use on your tax return.  One problem you may have is that less tax is withheld if you say you are HOH on your W-4, so your refund may be less or you might even owe tax due.

If you find that you need to change your withholding for the coming year, prepare a new W-4 for your employer for 2025.

https://turbotax.intuit.com/tax-tools/calculators/w4/ 

https://www.irs.gov/individuals/tax-withholding-estimator

https://www.irs.gov/pub/irs-pdf/fw4.pdf

And that stuff about "my parents want to do joined taxes" does not quite make sense here.   How your parents are filing their tax return has nothing to do with your own W-4.  Why did you mention that?

 Are they claiming you as a dependent?   If you can be claimed as a dependent by your parents, you must say in MY INFO that someone else can claim you.

To file as Head of Household, you have to:

• Pay for more than half of the expenses for a qualifying household
• Be considered unmarried on the last day of the tax year
• Have a qualifying child or dependent

To be claimed as a dependent on your parents return you must meet either the qualifying child test or the qualifying relative test.