I do not even know his name. However, there is only one reason the organization would delete a file on someone. Namely, death. If he passed away before the Death Game... And his file was then restored... Perhaps that means... he was revived. 

Sou Hiyori aka “Midori” - The main antagonist throughout the last half of the game. He’s the fourth and fifth floor’s floormaster. He has a sadistic personality and seems to find joy in everyone’s suffering. He is a main/supporting character throughout the last half of the game with many emotional lines.