OK, now I’m confused because this forum topic started off with Luminescence, then you meant to do it for Celestial Reloaded, now Preference?
So which theme should this whole topic be related to, because I need to move this topic to the appropriate forum category for the theme which looks like is for Preference.
For Preference your CSS would be:
.entry-footer,
.nav-single {
display:none;
}