Here's the trick I use with five-week old chicks to teach them to go into the coop at night.
First, I train them with treats to come to me when I use a signal. I use a pet training clicker, but you can use anything that suits you. This training sticks for life, and it's invaluable to round up your chickens very quickly if you have the need. Produce the treat and at the same time, use your signal. Do this for several days, and they will get it pretty quickly.
Then, when you're ready to have them learn to go into the coop, wait until it's nearly dark, get inside the coop, if it's not one of those tiny doll house types, and use your signal. When they come in, reward them with the treat. Then close them inside for the night.
Do this each night, and it usually takes only two or three nights and they will be going in on their own.
If at first they balk, get outside the coop at the entrance and use the signal. Reward them when they come to you. Then toss a treat inside the coop and see if they'll go in. If they don't at first, put each of them inside. Chickens are fast learners.
But since these guys are older and entrenched in a habit, it could take a few days longer to get them out of the habit of sleeping outside.