AlarmManager am = (AlarmManager) getContext().getSystemService(getContext().ALARM_SERVICE);
PendingIntent pic = PendingIntent.getBroadcast(getContext(), 10, new Intent(getContext(), AlarmReceiver.class), 0);
am.cancel(pic);

AlarmManager am = (AlarmManager) getContext().getSystemService(getContext().ALARM_SERVICE);
Intent i = new Intent(getContext(), AlarmReceiver.class);
...
PendingIntent pi = PendingIntent.getBroadcast(getContext(), 10, i, 0);
am.setRepeating(AlarmManager.RTC_WAKEUP, tm, period, pi);

public class MyReceiver extends BroadcastReceiver {
    public MyReceiver() {
    }
    @Override
    public void onReceive(Context context, Intent intent) {
        if (Intent.ACTION_BOOT_COMPLETED.equals(intent.getAction())) {
            Calendar cal = Calendar.getInstance();
            Intent aIntent = new Intent(context, SystemService.class);
            PendingIntent aPintent = PendingIntent.getService(context, 0, aIntent, 0);
            AlarmManager alarm = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
            alarm.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), 60 * 60 * 1000, aPintent);
        }
    }
}