It's a little complicated, but in the game's Images folder found in "Program Files" on windows, there are a bunch of image files that are used to create the lights. If you changed some of these to be invisible, the lights will not show up on the game. These files are named "LightSourceMask100.png" with the "100" changing in each file depending on the size of the light.

The tricky part is the game does not let you turn off each individual light.. For example, if you take away the light over the living room, most of the other big lights illuminating the game will go away too.

It would take some experimenting, but I'm sure we could do something about some of the lights like the little ones around the bedroom lamps or something. If you're not sure how to do this with an image editor, one of our modders can try it for you and give you the modified game files.

Also need to make sure you have access to the Images folder, there can be issues with this for Mac users.