If you're a resident of New York, submit MD form MW507 to your MD employer to stop the MD withholding. Here's a link to that form:
https://www.marylandtaxes.gov/forms/current_forms/mw507.pdf
Check box 3b on the form.
Also, since your income (as an NY resident) will be 100% taxable by NY, and since NY taxes are not being withheld from your pay, you should make quarterly estimated tax payments to the State of NY. This web reference gives the details on that:
https://www.tax.ny.gov/pit/estimated_tax/default.htm
My answer assumes that New York is your state of residence.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
