Hi C.,
That is ridiculous! My son had a night time bottle and he finally gave it to me 1 night. He does not transition well cold-turkey except when he makes that decision. I think he was about 18 months when he gave it up.
If you want to do, do it gradually, not all of a sudden. That is not right. If she drinks 8 oz, then put 7 oz in 1 oz water, do this for 2 to 3 nights, then 7, then 6, then 5 and so forth...I did that with my son, but he still wanted it. He was getting water and not just the formula, so I think that is much better.
DO NOT DO MILK, unless you know she can tolerate it!! Try it out in a sippy cup w/ just a few oz, she could be allergic, my son was and so I had to do Soymilk. He could still eat Mac & cheese & yogurt, but it wasn't the milk per say, it was the concentration of milk that gave him hives!! So, be careful!
Good Luck!
Gladys