There, he will read a poem written by Sayori named “%”, with the words “Get out of my head” repeated constantly. Sayori will then say the following: “…” How does sayori die? If you delete her while the game is open, and then start a brand new game (where you have to input a name), everything will seem normal, but then Sayori will appear, and she will appear confused. What happens if you delete Monika and sayori? So, in a desperate bid to try and rescue the happy ending she tried to give you, she attacked Sayori. Monika recognized that you, the Player, deleted her likely for ALL the other girls, not just Sayori.
You might be interested: Often asked: Romanticism and literature? Why did Monika kill sayori?