You will have to prove that you are a commercially rated UAV pilot. I don't know what the qualification is in Italy but in the UK it is called a PFCO (Permission For Commercial Operations). You contact Yuneec and provide the proof that you are commercially rated. They will then send you a file to disable the NFZ and instructions on how to do it via the GUI.
Since you are in Europe I'm pretty sure you still have to send it in to yuneec to get the NFZ removed.
But it is pretty straight forward send yuneec a email and they will help you with the process if you have a commercial license.
Definitely remember using the GUI when I did mine and mine's a TH. Yes, you do have to enter the code that they send you. I seem to remember that you have to be connect to the GUI and then you have to power off your H to complete the process.....