I don't think you can teach a chicken to not eat cat food. They love it. I think you just need to figure out a place for the cats to eat, safe from the chickens.
We have several cats, most of which go in and out, and we feed them indoors. But we have a couple of them who don't get to come inside to eat because they had started spraying indoors. Chickens love cat food, and we have dogs, too, so we had to figure out a way to feed the outdoor cats, without leaving cat food for the dogs to scarf down, or for the chickens to get. What we did was build a small "cat house". It's about two feet tall, two feet wide, and 5 feet long, with two compartments. Each compartment has a cat flap on one long side, for the cats to come and go. The cat flap wasn't enough, because when we got another, smaller dog, she was able to stick her head under the flap and steal the cat food. So we put a couple of doors that slide open on the opposite long side, and that's where we put the food dishes. The cats come and go as they please through the flaps, the dogs can't reach the food, the chickens can't manage the flaps. It works great. The outdoor cats get fed, and they have a shelter as well.
We use heavy ceramic containers for the food. Lighter ones, like plastic bowls, get knocked over when empty, pushed around, and can be hard to reach. Ours are ceramic popcorn buckets we found for about $2 at a thrift store. They hold about 5 cups of food each.
People worry about cats bothering or killing chickens, but in my experience, except for baby chicks, the chickens intimidate the heck out of the cats, and sometime attack them. I saw an 18 lb. Maine Coon cat beat up by a 1/2 lb. banty hen.