There is an option to hide the "Duplicate Items" and "Unfiled Items" from the context menu. To display these again, use the library's context menu.
I don't see the point of hiding a collection in a library. If you want to reduce clutter, consider creating a new collection (e.g., "Hidden") and nesting some collections underneath. Alternatively, you can delete the collection and leave it in the trash until you're ready to restore it.
I don't see the point of hiding a collection in a library. If you want to reduce clutter, consider creating a new collection (e.g., "Hidden") and nesting some collections underneath. Alternatively, you can delete the collection and leave it in the trash until you're ready to restore it.