Hi Lyn,
The functionality you described is covered in recent improvements to the Report Builder (TL-17930). It will be included in one of the upcoming Evergreen releases and eventually land in Totara Learn 13.0.
With this improvement you'll be able to create a saved search on a specific report (e.g. hide all canceled events) and then set this filtered view as default view for that report for all users.
Thank you.