There are several ways to delete items to the calendar.
If the pop-up menu triangle is visible next to the item, as in the Day window, click it and choose Delete from the pop-menu.
Another way to delete an item is to hold the Command and Option keys down and click the item. An eraser cursor appears while clicking with the Command and Option keys. If you want to change your mind about deleting an item, move the cursor away from the event before releasing the mouse. If Confirm Deletes is turned on in the Extras menu, then a confirmation dialog will appear when items are deleted.
See Adding Items, Changing Items, Rescheduling Events and Labeling Events.
