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In order to delete attendance, click on Delete the checkbox under the Action column in the Manage and Report Attendance Tile. 
Select for Deletion column on the Attendee Index. Multiple lines can be selected.
Once you select one or more individuals to delete, the Delete button will be enabled. Select the Delete button to delete the attendance of the selected individuals.
This will prompt a pop up message to confirm. Click "Yes" to affirm the deletion.
The deleted attendee(s) will no longer appear on the list of attendees.