That is not a standard approach. If you need dynamic lights, you are probably better of with dynamic lighting. But if you want to mess with the lightmaps, then you can access them via the LightmapSettings-Class:
var lightmaps = LightmapSettings.lightmaps; lightmaps[0].lightmapColor = new Texture2D(256, 256, TextureFormat.ARGB4444, false); LightmapSettings.lightmaps = lightmaps;
This code will replace the color component of the lightmap with a black texture.