File a new W4 with your employer. From the instructions:
Complete Form W-4 so that your employer can withhold the
correct federal income tax from your pay. If too little is withheld,
you will generally owe tax when you file your tax return and may
owe a penalty. If too much is withheld, you will generally be due
a refund.
If you feel the correct withholding is "$0.00", W4 is how you tell your employer to not withhold anything for taxes.