The Recently Cancelled Trainings tool here works just like its VSys One equivalent, showing you training records with a Status of "Cancelled by volunteer" during some time period. Use the filters at the top to select the cancellation date range, start date, subjects, etc. Then click Refresh to load the training records.
Click on the person's name to open their profile in a new window; use the Edit link to edit the training itself.
Changes made here are saved immediately.