If he rebuilt the skin from the ground up, then he can legally remove the copyright notice as this is considered a "derivative work" under US Copyright law.

As long as it's an "original work of authorship", even if it's based upon an existing work, it's still legal. Us courts have upheld this multiple times:

Sega Enterprises, Ltd. v. Accolade, Inc.

Lewis Galoob Toys, Inc. v. Nintendo of America, Inc.

While the "derivative work" law on software is not completely clear, this does not fall under the realm of software since it is a design in question.

I'm not saying either side is right or wrong and only a code analysis could truly prove if the OP did indeed infringe upon the rights of the original author, but I had to clarify some misconceptions I've seen here about copyright law. As a coder, if someone saw a mod that I've written and completely designed their own - with similar functionality - from the ground up utilizing none of my original code then they are not in violation of anyt copyright I may claim over my work (unless such work is protected by a patent - and nothing here is).

My information is cited from Wikipedia, http://en.wikipedia.org/wiki/Derivative_work

Exactly. I am not violating anything considering its "derivative work."

I've just very briefly gone though both sets of code. It looks like you may have made some significant changes to 4 of 5 templates - the other 130 or so are pretty much the same as the original work by ElForro as is all CSS. Try having a look at yours and ElForro's xml files side by side and you'll soon see just how little is different from the original.

With my original post I wasn't intending on getting into this debate, I was just questioning if you had requested permission from the original author to use his code and remove his copyright notice which you had not. Send him a message, he may just say yes.