Add item to config & remove item from config

I've been looking on forums and I can't find something, I have no idea how to delete an item as I see no functions for it, and when I try to add another item, it always replace the first one I'm using craftbukkit 1.6.4 . Here's my code.

Code:

if(!args[0].equals("")){
    if(args[0].matches("(\\d{1,})[:{1}](\\d{1,})")){
        String string = args[0];
        String[] parts = string.split(":");
        Integer part1 = Integer.valueOf(parts[0]); 
        Integer part2 = Integer.valueOf(parts[1]); 
        String igitems = "IgnoredItems";
        getConfig().set(igitems + ".itemid", args[0]);
        saveConfig();
        sender.sendMessage(prefix + ChatColor.GREEN + "Added " + ChatColor.GOLD + args[0] +          ChatColor.GREEN + " to ignore list.");
    } else {
      sender.sendMessage(prefix + ChatColor.RED + "Invalid Paramaters. Remeber to add " +                ChatColor.GOLD + ":0 " + ChatColor.RED + "if it's a normal ID. Example: " + ChatColor.GOLD + "/addignore 2:0 " + ChatColor.RED +"for a grass block.");
 
}

 

just set the configuration section where you keep the item stacks to null then save it

 

To remove a node in the config, set it to null.

Code:

getConfig().set("your-path",null);

 

Got it for the remove, but still can't figure out how to add more than one item with the addignore command, keeps editing the first one without adding any new one

 

do
config.set("item.1",item1)
config.set("item.2",item2)
config.set("item.3",item3)