He's still a counsellor of state.
There are no counsellors of state at the current moment, as one hasn't needed to be formally appointed since 2015. While you'd be correct to point out that Andrew is currently one of only 4 people who are legally eligible to be appointed as one, that's only the case because of his princely status that emanates from his birth; short of an Act of Parliament, there exists no mechanism to either take that away from him or revoke his eligibility for appointment as a counsellor of state. In any event, he'll technically still be eligible for appointment as one 'til Charlotte turns 21 in 2036, but it's beyond clear that neither his mother nor brother would ever willingly appoint him as a counsellor of state in either of their absences anyway.
Of course, nothing's stopping Parliament from passing a bill of attainder formally removing Andrew from the Royal Family.