When you create an event or a to-do, and add attendees to it, you are acting as the event organizer. To add attendees, use the attendee tab, in the Edit Event, or Edit To-do dialog. In the Agenda view, a little icon is placed in the event, if you are the organizer of a group scheduling event.
The organizer is responsible for sending the invitations, collecting the attendees responses, and for keeping the data of the event or to-do up to date for all people involved.
To organize an event or to-do, create it in KOrganizer and add all the people that should attend using the attendees tab. KOrganizer can send invitations to the attendees, either automatically (depending on KOrganizer group scheduling configuration), or by selecting the event or to-do and choosing the → menu item. The attendees get an email containing all the relevant information for the event or to-do. They can respond to the meeting proposal by accepting or rejecting it or by making a counter proposal. They can also delegate or forward the invitation. All this information is sent to you by email again and, if you have configured KMail appropriately, the attendees responses are automatically inserted in your calendar. If there are additional attendees willing to participate (e.g. by accepting a forwarded invitation) you will be asked to accept the new attendees.
To cancel an event or to-do you have to be the organizer. If you checked the Use Groupware Communication box in the KOrganizer group scheduling configuration, just delete the item, and KOrganizer will ask you to send the cancellation. If not, simply select the item, and choose the → menu item.
This action will send a cancel-message to all attendees, so they can remove the item from their calendars too.