This reference explains NY's filing requirements for non-residents:
https://www.tax.ny.gov/pit/file/nonresidents.htm
If you do have to pay NY income tax, you would claim a credit for it on your home state PA tax return, not on your non-resident DE tax return.
Credit for income tax paid to a non-resident state is granted by the taxpayer's resident state.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
