Once you become Chuunin you have the option of leaving the village. Once you decide to leave the village will be classified as a Missing Ninja(aka Rouge Ninja) and will be put in the Bingo Book. You will be wanted.

To leave you must write a 10 line post on leaving and why you are becoming a Missing Ninja. Once you post anyone from the village has 10 hours to try and catch you. Once caught you must fight and win to keep going and if you lose you are brought back to the Village to be punished.

Lastly once you are a Missing Ninja you can associate to see if you have the requirements to join the Neo Akatsuki.