Zone is a time interval plus resources (the corresponding ScheduleView class is called Slot) - you could check our Special Slots example for more information. What I was suggesting is to create a read-only slot for every appointment that should not be deleted. This will make the appointments read-only, though.
If you want to make them only not deletable, but editable, you should cancel the AppointmentDeleting event. The X button chould be removed using a custom AppointmentItem Style that redefines the AppointmentItem ControlTemplate.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!