How to stop Chickens from sleeping in nesting box

[TerryE]

How do I stop one chicken from sleeping in nesting box and fouling it.?

 

[Ol Grey Mare]

Depends on your setup and why the bird is doing it...ie just habit, bullying, lack of roost space, inability to get to the roost, etc.
For simple "just habit", a simple step is to move the bird to the roost and generally they get the idea after a few times.
Other causes require addressing the cause and behavior

 

[Sharwig]

I had a couple hens that fancied sleeping in the nesting boxes. I covered the nesting boxes at night which seemed to discourage the bahavior and I don't have the problem anymore -- but you have to remember to remove the covers each morning

 

[Irishsilk]

And making sure your perches are higher than the nesting box.