A Save editor is a piece of software that modifies a save file. Games installed and played on a personal computer are unique in that the saved games are external files that can be copied and modified. Third-party software is sometimes offered to modify these game files. While this can be used as a cheat code to improve stats and other character assets, it can also be used just to change the name and other data that does not affect the game.
Browse and buy a save editor online. Some are built by the same company that manufactures a game while others are built by fans who just want to tweak their game files. Most are free as it is unethical to charge and reap a profit from a proprietary game. The save editor you want could be among a list on this popular website.