Are you talking about box 15 on the W-2? Boxes 15-17 refer to information about withholding state income tax - but Washington State doesn't have an income, so boxes 15-17 should be blank.
If you are talking about boxes 18-20 (the same thing but for local taxes), did you auto-import your W-2? In some cases, the auto-import may leave garbage data in some of these boxes, so they should be blank also.
Tell me, is it possible that you have any local taxes where you live in Washington?