Well, an 'erased visual novel' is basically a form of digital storytelling. Visual novels usually have text - based stories with some pictures or simple animations. The 'erased' part could refer to various things. It could be that parts of the story are about things being erased from the characters' lives, like forgotten memories or removed relationships. It might also suggest a unique gameplay mechanic where the player has to 'erase' certain choices or paths in the story to progress.
It could mean that the boy removed or wiped out a story. Maybe he erased a written story, like from a piece of paper, or perhaps he's trying to forget or hide a story that he knows.
The ending of the Erased manga is quite complex. The main character finally uncovers the truth and achieves a sort of resolution, but it's not a straightforward happy ending.