In the MY INFO tab simply remove the dependent no longer wanted. 

If this is on an already filed return you will amend the return and then remove the child. 

Are you asking about removing dependents from your tax return, or changing the number of dependents on your W-4? If you are asking about your tax return see Critter-3's reply. If you are asking about your W-4, just fill out a new W-4 form without any dependents and give the new form to your employer. Your employer should be able to give you a new W-4 form.

Thank you this was a big help!!!

Critter-# was what I needed, thank you.