Any time you use AutoFill you can later clear the assignments if you like.
To set all shifts back to unassgined use the Clear / Delete button.
To clear (unassign) just shifts you most recently AutoFilled you can use the Schedule Grid. Sort by the “Last Edited” column and check off the first row and then then shift-click the last row for the date/time you AutoFilled and then click the “Unassign” link below the grid.
delete previous entry delete previose entry undo action