Removing GUI from Player Ranks Plugin

Hey everyone, I've been staring at this code for hours not knowing what to do, does anyone have any experience with messing with the "Player Ranks" plugin by Steenamaroo? What I want to be able to do is remove the in-game GUI so it can be usable on my community server, and then allow the leaderboard aspect of the plugin avaliable on my tebex website (if possible).

As this plugin is from another site and the dev is at the other site you would be better of asking him for help ?