Editing / deleting of recurrent events requires an extra step when using the Google Drive API.
First of all, a recurrent item consists of two type of events. The first is the parent event which contains the Recurrence string. The second are the instances of the recurrent item. By design, only the instances are retrieved when requesting a list of events.
To edit or delete the recurring event you first have to retrieve the parent item separately.
You can do this by using the RecurringID property value of one of the instances as the ItemID parameter for the GetItemById call.
After updating the parent item, the instances will also be affected.