Is there a way to purge multiple Google Calendar entries at a time? For example, is there a way to clear a day, week, or month at a time?
Currently, there is no way to do this in Google Calendar. You could import/export the google calendar to another web app or desktop application which has this functionality, make the necessary changes and then sync the calendar back to Google Calendar as a workaround.
You can use something that has this functionality and can sync with Google Calendar (iCal (Mac OSX) or Evolution (Linux), I'm not sure what can do this on Windows)