Slowly drag the timing (example: you pump every 6 hours now, then slowly drag to 9 hours then 12 hours), drop the number of pump session (example: you pump 4 times a day, then drop to 3 then 2 then 1). Alternatively, you can eat medicine to stop milk supply.
you can try this "no more milk tea" from Earth Mama to slowly wean off. https://s.shopee.sg/9zhT9wDMmy
I've heard cabbage leaves work. but just reduce the milk slowly until you can comfortably stop