Only holiday and General events can be edited from the Calendar. Other events such as examinations and book/fee dues must be edited from their respective modules.
To edit a holiday event:
To edit a holiday/general event: At the top of your dashboard, click the module access icon > Academics > Calendar to open the Calendar.
Hover over the green/black icon that indicates a Holiday/General Event. The event details are displayed on the right.
Click Edit beside the event details.
Make the changes and click the Update event button.
For more information, watch this-