Trying to remove "default" permissions group if player has it.

Hi, I've been trying to make it so that the SignRank plugin does not only add a group when you hit a sign but also removes the group named "default" if you have it.

So, after the player is promoted to the group specified in the config (line 39 I think)
the plugin checks if they are also in the "default" group and if they are, it removes that group from them.

I'd be very happy if someone could tell me what code to add and where.
The plugin uses Vault.
Vault API: http://mythcraft.dyndns.org/javadoc/vault/
SignRank code to be changed: http://pastie.org/3761383

Thanks for any help

Someone gave me this code to try: http://pastie.org/3762511
but it didn't work, can anyone tell me why?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.