To Cancel a session with one of your patients, go to your Sessions List on the left side-bar. Next to the session you would like to cancel click the red "Cancel" button.

 

You can also go to My Calendar, click on the Scheduled Session event, click Edit, and click the red Cancel button at the bottom.

 

For both, you will be prompted "Are you sure you want to cancel this session?" Click "OK" or "Yes".

 

Your patient will then be notified via email about the canceled session.