Why Can't We Delete Appointments from the Daily View?
As you know, there are no dialogs in Instant Web Publishing, so when you delete a portal row, you don't really get a warning (with the status bar hidden, you don't even get a submit or cancel button). Accordingly we've required you to go to the appointment's form screen (by clicking on the appointment) where you can then delete it using the tools in the status area on the left side of the screen. These tools do give you a warning before actually deleting your record.
Should you want to delete without a warning dialog right from the daily view, copy one of the trash can icons from another screen and paste it into the appointment's portal row. Change the trash can field to be from the AppointentsDailyInterface table occurrence: the icon already has the delete portal row action assigned to it. Switching its table occurrence is all you need to do to get it to work.