Cancel UILocalNotification:

NSString *myIDToCancel = @"some_id_to_cancel";
UILocalNotification *notificationToCancel=nil;
for(notificationToCancel in [[UIApplication sharedApplication] scheduledLocalNotifications]) {
  if([[notificationToCancel.userInfo objectForKey:@"ID"] isEqualToString:myIDToCancel]) {
     break;
  }
}
[[UIApplication sharedApplication] cancelLocalNotification:notificationToCancel];