Yes, you have to file in both states. Rental income from properties located in NC is taxable by NC. And as an SC resident, ALL your income (including the rental income from NC) is taxable by SC.
You'll be able to take a credit on your SC return for the taxes paid to NC, so you won't be double-taxed.
https://ttlc.intuit.com/questions/1901271-how-do-i-file-a-nonresident-state-return
**Answers are correct to the best of my ability but do not constitute tax or legal advice.