First I can hide it from the camera but lately I still see it through Glass BSDF material. I take the screenshot for the following problem.This screenshot from inside the room:
And this screenshot from outside the room:
We can see the reflection of the invisible Emitter mesh in the window glass.
And, how to hide it from Glass BSDF material?
I don’t know how to hide the emitter from only that window glass reflection, however this may help: https://www.blender.org/manual/render/cycles/settings/light_paths.html#ray-visibility
-select the emitter mesh
-in the Properties Editor go to: Object ‣ Cycles Settings ‣ Ray visibility
-deselect glossy and probably in you case also transmission.
