Closing out appointments in the calendar section helps to stay organized and quickly determine which appointments to focus on.
Users have the ability to close out appointments manually. After the appointment status is set to "Show", "No Show", "Cancelled", etc., the final step is to click the close button to remove the appointment from the calendar.
If the close button isn't clicked after updating the status, the appointment will remain on the calendar for 5 days, with an exclamation mark, then close out automatically. Appointments that are not updated and left in "Scheduled" status will close out as a No Show.
For more detailed information on appointments, please click link
http://help.ynot.us/prospects/working-leads-and-identifying-prospects/64-set-reminders-with-appointments-callbacks