Add or remove shared folders and files in iCloud Drive
After you share a folder, you can add folders and files to it and all participants can access them. If you remove a folder or file from a shared folder, all participants lose access to the item. All participants who can change the files can also add and remove folders and files.
Add a folder or file to a shared folder
In iCloud Drive on your Mac, drag the item to the shared folder.
When you place a file that you have already shared with others into a shared folder, only the participants of the shared folder can access the file. Participants who previously had access to the file lose it. You can also move a shared item which you don’t own into a shared folder.
Remove a folder or file from a shared folder
In iCloud Drive on your Mac, drag the item out of the shared folder.
All the participants of the shared folder lose access to the item.