At the bottom-right corner of the preview window, click the second color picker and choose whatever "lit" color you want. Turn off all lights and remove/hide glowing objects.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)