The simplest way is to just clone the code and start hacking away improving the design. You'll want to look at the "Gilded Rose Requirements" which explains what the code is for. I strongly advise you that you'll also need some tests if you want to make sure you don't break the code while you refactor.
You could write some unit tests yourself, using the requirements to identify suitable test cases.
The idea of the exercise is to do some deliberate practice, and improve your skills at designing test cases and refactoring. The idea is not to re-write the code from scratch, but rather to practice taking small steps, running the tests often, and incrementally improving the design.