You must pay state income tax if you are domiciled in that state. Your domicile is your real permanent home. There is no single factor that determines where your domicile is, it depends on a combination of all your facts and circumstances such as your home, business relationships, social relationships, church, doctor, voter and car registration, etc. Changing domiciles requires both taking steps to establish a new domicile and taking active steps to abandon or leave your prior domicile. It is possible to live away from home for a long time without actually changing your domicile.
So the question you have to answer is, have you changed domiciles, and when did that actually happen? For example, if you maintain a home in North Carolina that you visit for a few weeks a year, and you keep your US voter registration active in North Carolina, then the state of North Carolina may view that you never abandoned your North Carolina domicile and are still required to pay North Carolina state income tax. Or, the facts might show that you maintained a North Carolina domicile, intending to return, and only abandoned the domicile when you decided to remain in India after retirement.
If you determined that you were not domiciled in North Carolina for 2019, 2020, or 2021, you can file an amended state tax return to claim a refund of all your withheld taxes. You would file the amended return as a non-resident and report zero NC-sourced income. Previous years are too old to amend. Also note that if you had North Carolina-source income, such as the sale of property located in the state of North Carolina, you must report that as taxable income on a non-resident return.
