In the absence section, you can add and remove attendees from the absence list. To access the absence section, you need to be in admin view.
To add participant to the absence list:
The delegate is now absent and cannot vote as long as he or she is on the list.
To remove participant from the absence list:
In the navigation panel on the left, you can see which attendees are absent from which section.
Under absence history, you can see when delegates left and returned to the meeting, as well as read any comment.