Instead of deleting and re-entering just the W-2, have you tried deleting or starting over the entire NJ return?
How do I delete my state return in TurboTax Online? (intuit.com)
(Obvious but maybe worth checking) Are you sure that in My Info you answered NO to the question about having income from other states?
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
