Summary:
Auto populated holidays are timeoff's booked automatically by the System. Deleting timesheet from Historical Timesheets will not delete the Booked Time Offs. This is also true for any other type of booked time off. When the user clicks on the timesheet the Booked Time Off would appear again. The correct way to delete the auto populated time off is by deleting it from Historical Time Off. Once deleted, the Time Off Bookings will not appear on the timesheet.

Steps to delete the Booked time off:

Log into Web TimeSheet with Administrative privileges.
Click on Administration tab.
Click on Historical Time Off.
Auto populated holiday will be one of the items in the list. Locate the Holiday for the correct user.
Highlight the Time Off to be deleted.
Click on Delete button below the screen to delete the Time Off. (One can also click the red x in a circle icon next to holiday to delete the Holiday).