Album art is usually displayed in-terminal, within the main program window. As such, you cannot independently stop the album art being displayed: there's no separate window to close, accidentally or otherwise. If you close the terminal it's displayed in, you'd end up closing the entire Giocoso program too!
However, if you have edited the Persistent Configuration file and set the 'Display Album Art in own window' option to 'yes', then album art will be displayed in an independent window, external to the main Giocoso program window. It will have its own window title bar, complete with minimise and close buttons ...and you may accordingly close this new window without interrupting Giocoso's playing of music. In which case, you'd no longer be looking at the album art, but you'd still be listening to music playback. That, in turn, gives rise to the potential need to re-display the album art window that was previously closed. This is what the Administration menu Option 6 achieves.
It simply fetches the album art of the currently-playing recording and displays it again in an independent window. This window then has an independent existence: it will continue displaying the same album art for as long as you let it. If Giocoso starts playing a new recording, with its own, new album art, it will not update the display of the pre-existing album art window. Only by re-taking Administration menu Option 6 again will the first window be killed off and a new one (with the new album art) be opened. You can keep taking Option 6 as many times as you like: each use of it will kill the existing album art window and open a new one, displaying whatever the currently-playing recording's album art happens to be.