Like weaning from the breast, weaning from the pump is best done gradually. That will give the mother's milk supply time to adjust, reducing engorgement problems, and also give time for her baby to transition to other milks. I would suggest cutting out one pumping session and try that for a couple weeks. If she gets engorged, she can pump just enough to relieve discomfort and prevent leaking.
Her milk supply will decrease, but this usually happens naturally at that age anyway, and as long as her baby is eating other foods it shouldn't be a problem. A lot of the calories the baby got from pumped milk will be replaced by weaning foods, and other milks can be used to fill in the gaps. If her baby is not eating much in the way of solid foods it might be harder to break away from the pump.
I started weaning from the pump at 13 months. I pumped in the mornings, nursed Chace during my lunch break, and then skipped pumping in the afternoons. He was usually willing to wait for me to get home, but if he fussed a lot, DH would give him soy milk in a bottle. A month later, I broke my arm. I was out of work for two months, and when I went back I started working part time only. At that point I decided my pumping days were over. Chace usually doesn't need any milk while I'm gone but if he starts crying for "boom-boom", dh gives him a soy milk bottle. Of course when I'm home and he wants "boom-boom", soy milk is out of the question