Use dtcm_delete from the command line to delete appointments from your calendar. For example:
system% dtcm_delete -d 11/1/1994
Appointments for Tuesday November 1, 1994:
1) 10:00am-11:00am one-on-one
2) 11:30am-12:30pm workout
3) 12:30:pm-1:00pm eat lunch
Item to delete (number)? 3
Appointments for Tuesday November 1, 1994:
1) 10:00am-11:00am one-on-one
2) 11:30am-12:30pm workout
When you don't want to delete any more items, press Return.