NJ does not tax non-resident remote income. If you never resided in nor actually (physically) worked in NJ during the tax year, then your work income is not taxed by NJ.
If this is your situation, and your employer mistakenly withheld NJ taxes from your pay, then the procedure is to file a non-resident NJ return on which you report the withholding but allocate zero income to NJ. This should result in a full refund of the incorrectly withheld NJ taxes.
Your income is of course 100% taxable by your home state of MO.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
