Be sure to remove eggs from under the hen regularly and, if possible, pick her up and set her away from the nesting area while you collect them.
Create a separate environment for her using a small portable coop or crate. Removing her from the nesting boxes and eggs could help get her out of the broody mindset.
Putting her in a cage with a wire bottom, open to the air, can help cool her underside and disengage her from the broody feeling.
If using a wire-bottom cage doesn’t work or isn’t an option, some people slip a few ice cubes under a broody hen a couple of times a day, which can result in cooling her temperature and making her “nest” undesirable.
Similar to the ice cube method, some people have found success by simply dunking the hen’s underside in a shallow dish of cool water.