To cancel shifts in bulk:
Select the workers you would like to cancel shifts for using the tick boxes or use the 'all' link to select everyone
Click the 'Batch Edit Shifts' button
All shifts highlighted in green will be amended, deselect any shifts that don't apply by clicking within the box
Select cancel - the number of shifts being cancelled will be shown in brackets
If shifts have been 'published' you'll need to select a reason for the cancellation