If they are turned off, they aren't doing anything except taking up space.  You should be able to delete them without affecting your lighting.

Turned off lights also count towards the 8 lights that Poser 6 and up will preview.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi