Not sure if perhaps a bug but in a very simple scene after building my lightmaps using GPU LightMass in UE 5.1 I am unable to delete them.
ie Force no precomputed lighting is enabled and I complete an additional buiuld.
Have done several times and even relaunched my project. Lightmaps are still there!
I believe the lightmap data is actually embedded in the level asset so cannot simply delete from the desktop.