As in, can you delete the items displayed in recuva or is it impossible?

You can never delete them, they are after all deleted files. You can use Recuva to overwrite the file data (with the Secure Overwrite facility) which will make the data useless if it is recovered by any means. Recuva will not remove or overwrite the file or folder name so you will still end up with the same list whatever you do. Eventually these deleted files will be overwritten by new files, and further deleted files will appear. As long as you use your pc this cycle will never end.