I suspect that the lightmass lightmaps are taking up a lot of disk space in the umap file for my map. It seems wasteful to submit the lightmass assets into source control because they can be simply regenerated. So I would like to clear them out before submitting to perforce. Is there a way to se…

There’s no way to delete those assets from the map package manually. You can check bForceNoPrecomputedLighting and rebuild, that will cause them to be deleted.