Events marked "Read Only" cannot be edited or deleted in Smart Planner. They need to be deleted at their data source.
- For events shown automatically by Google Calendar, such as birthdays and holidays, change the relevant settings in Google Calendar (the birthday information in your contacts, or the holiday calendar subscription)
- For events in a view-only calendar shared by someone else, ask the calendar's owner to delete them
- For events added automatically from Gmail or other services, turn them off in the settings of Gmail or the relevant service
If you can't delete an event, hide the calendar in question from "Calendar Settings" → "Visible Calendars" in the settings screen.
Thank you.