Just stop it. There is a medicine used for patients who have Parkinson's Disease called bromocriptine which blocks the hormonal signals to your breasts and so "drys them up". Speak to your doc about it.
You pick. You can drop one feeding every couple days (formula instead) until off. You can allow 2-3 min/side each feed (follow with formula).This signals your body to slow production.You can cold turkey= bind your chest with ace wrap/pre-pregnancy bra and tough it out for a few days. Each of these 3 ways has pro's/cons, in the end only youcan decide what would work for you.