I have looked in People help. When in People view, how can I turn off the green rectangle in the viewer, when viewing photos of selected individuals?
You mean in the Viewer?
Key sequence A,E will show/hide annotations, including the face annotations. Also available (and mentioned) in the context menu, sub menu "Display options".
For the Quick View Panel the hot key is <A>, also available via in the right-click menu.
Thanks both.