If you have already created and made a repetitive event and need to edit, modify or delete recurring event in Google Calendar on your Android device, then you should do as follows:
1. Open Google Calendar
2. Tap the event from the series of recurring event
3. the details of that event is shown. Tap the Modifying button (it is like a pencil)
4. Now choose one of these options: Change only this event, Change all events in the series, Change this and all future events
5. Go to Repetition and do necessary changes. Turn it off to delete the recurring event.