If volunteers have signed up for a shift, or you've assigned volunteers, but the shift itself is no longer needed, you can cancel the shift.
Click on the shift anywhere in the schedule and click 'Edit Shift'. In the top right corner of the Edit Shift pop-up, there's a dropdown that says 'Published'. Click on 'Published' and select 'Canceled'. Click Save Changes.
The shift will still appear in the schedule, but will be cancelled. It will show as empty, with a red icon to indicate it's status as a cancelled shift. To assign anyone to the shift, you will need to edit the shift again and change the status back to 'Published.'
In the profile card, volunteers who were confirmed for cancelled shifts will still have the shift in their Activity tab, but with the status 'Cancelled'.
When you cancel a shift, a shift update will appear in the Shift Updates tab for any volunteer who was confirmed for that shift. You will need to notify your volunteers of the cancellation in the Shift Updates tab.