Folders stored on the PrivateStorage network can only be retrieved and decrypted by someone holding the capability. When you delete files or folders from your computer, the PrivateStorage client also forgets the corresponding capabilities. At this point, it becomes impossible for that client to retrieve and decrypt the content. If all clients forget the capability for a file or folder, no one can retrieve and decrypt the content. At some later point, the storage grid will reclaim the space that was allocated to the encrypted content.