Welcome to Flyertalk and welcome to the BA forum AAFlyer2019, it's good to see new members here and I hope you will make yourself at home here.

If there are no 2-4-1s or similar vouchers involved and it's a straightforward Avios redemption then it should be fairly easy. You need to call up BA, get them to split your original reservation so that you are on your own PNR, and then get them to delete the last sector. It's just a few key strokes. So long as you haven't yet started the trip then you'll even get the last set of Avios back. You could also do nothing, but then you wouldn't get the Avios back, you're not required to be present for the final sector. If there are other sectors after IND then it gets (slightly) more complicated. If you have checked baggage then that is supposed to be labelled to IND, but of course the procedure is that you have to claim luggage for Customs at JFK anyway.

If you do split the reservation, make sure the agent puts a note on both reservations cross referencing. It doesn't do much good but it helps if there irrops or similar.