The number you claimed on your W-4, at work, was just an estimate. You don't enter it
anywhere on your actual return. It does not lock you in on what you can claim,
at tax filing time. The IRS does not try to match that number with the actual
number of exemptions you end up filing for.
In TutboTax (TT), you simply DON'T check the box that says you can be claimed as a dependent by someone else.