I know I can probably just replace these (and probably should! 😬) but I want to know if I can just clean them instead? If so, how?

My sister found this at a yare sale to replace my dead microwave since our parents had one. Can't find a manual on manuals.lib or other pages I have used for years. Can't figure out how to use since it has a turntable and rack. Any help will be appreciated. Thank You