If you need to delete duplicate events that have been imported into Outlook, you can search for the text, CalendarWiz, and it will list all events that were imported from CalendarWiz (we place this text into the description of each event imported).
To do the search, go to your Outlook calendar, click on Find, enter, CalendarWiz, into the "Look For" field, select Search In Calendar and click on Find Now.
This should list all imported events. You can then click on the first event, scroll down, hold the Shift key down and click on the last event. Then you can delete all the events at once.