To cancel your subscription to a calendar, check the box next to its name in the Merged Calendars list. Then click the "Remove Checked" button. Events from the calendar will no longer appear on your localendar.
For optimal performance, merged Merged calendars are currently refreshed approximately every 2 hours. every time your main calendar is refreshed. We may chose to cache imported iCal events in the future for performance concerns (for example, if the external site is taking too long to respond to localendar)