The credit isn't at the navbar.. it's at the footer? I create these add ons and release them free of charge. It takes time to create them and unfortunately as they say: "time is money". It's very inconspicuous right at the bottom of the forum. Your members aren't likely to see it, only people who will are those who look for it. (though I notice it's not the same color as the other footer links on your site. Add a css rule for .concealed to EXTRA.css if you want it to be the same color)
If you want a customization like this but you don't want to credit the author for his hard work, or pay for the customization, or show a credit, or use is under it's current conditions, then how about you simply don't use it? Learn XenForo like Mikey did and do this yourself?
