If you have already filed your tax return and it has been accepted, you will have to amend your return to change the box 1 entry on your W-2. Since box 1 is the amount of taxable income, it must be correct on your final tax return. An amended return is form 1040X which must be completed, printed, signed and mailed. It can't be efiled. Do no change your original return until you begin the amended return.
Here are instructions: https://ttlc.intuit.com/questions/4667233-how-do-i-amend-a-2018-return-in-turbotax
