The Appointments List tab primarily exists to list appointments that have some sort of problem that needs attention. When a problem appointment is created the tab will turn red and the appointment will be listed in red. There are several ways problem appointments are created.
Appointments created by the vendor that violate the rules set up in the UI Setup tab on the Settings tab will be flagged as a problem. These can be cleared by selecting the appointment on the Appointments tab and pressing the "Confirm Appointment" button. If there is a problem, the appointment will be outlined in red right on the Appointments tab when you make it. The reason for the problem will be displayed on the left, so you should be able to decide whether you want to confirm the appointment or whether you want to cancel it. So, generally these appointments won't ever make it to the Appointments List tab.
The screen below shows an example of a problem appointment. When the red box was selected the reason for the problem showed up under the calendar on the left. To force this appointment, select the Confirm Appointment tab.
If you did not force the appointment, this problem appointment would remain on the red Appointment List tab. When you select the red Appointments List tab you would see the following:
When you delete an event, the resources that are on the event will also be deleted. When a resource is deleted, the slots are also deleted. But when a slot is deleted the appointments on that slot will not be deleted. Appointments are not deleted, they are flagged and all flagged appointments show up in the red Appointments List tab on the Admin UI.
Here is a screen shot of an appointment where the time slot for the appointment was deleted. To recreate the slot select the problem appointment and click on the recreate slot button.
IMPORTANT NOTE: You will want to make sure that your Appointments List is not red and does not contain any red appointments. To the parent these appointments will still exist, and any reminder emails that have been set up will continue to go out.