If you use a computer and access iCloud Drive in the Finder Sidebar, what happens when you try to delete from iCloud Drive? If iCloud Drive isn't visible in the Finder Sidebar, go Finder/Preferences/Sidebar/Favorites and check the box.
If you go to iCloud.com/iCloud Drive using a computer browser, can you select a file, and tap the Trash can? What happens when you try to delete a file?