How to stop a service at a specific time of the day?

I have been able to start a service at specific time of every day but I want to do the exact same thing to stop but I don't know how.

Here is the code I use to start the service using AlarmManager.
note: I am new to android dev so providing a full commented code will be highly appreciated.

 Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, 9);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    PendingIntent pi = PendingIntent.getService(getApplicationContext(), 0,
            new Intent(getApplicationContext(), Service.class), PendingIntent.FLAG_NO_CREATE);
    AlarmManager am = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
    am.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),
            AlarmManager.INTERVAL_DAY, pi);