I would revisit the W-2 section to make sure there isn't an incomplete entry that is prompting this question. 

1.) Federal Taxes

2.) Wages and Income

3.) I'll Choose What I Work On 

4.) Click Update next to Wages and Salaries

4.) Click through the screens until you see a screen titled Here's your W-2 info

5.) Click Delete next to any W-2 entry that you wish to delete