Please ensure you've read the introduction to importing calendars.
✏️ Edits to imported events must be done in the source calendar:
Imported calendars are not editable inside Slack. Eventbot will pull in the external calendar, but it can't make changes to it. If you wish to edit any events on an imported calendar, go to the calendar source and make changes there. Eventbot will update the events in Slack accordingly.
✖️ Removing external events from your channel:
You can remove an external event from your channel. Like any other event, click "Details" then "Remove". To be clear, this will not cancel the event (as that must be done in the external calendar), but this will remove the event from your channel going forward.