No, you will need to let your employer know about the changes which need to be made so that a W-2C (Corrected) is issued to you. You will then have to enter that information from the corrected W-2. By simply making manual changes on your W-2 in TurboTax will create a mismatch since the information which you enter is verified against the information the Social Security Administration and IRS has on their end and it will create delays and may even result in penalties in interest.
The best approach is to contact your employer so that they can issue a W-2C and then you can enter that in TurboTax.
