Detecting files like in Doki Doki

so i played doki doki and i wanted to know, how do we insert or detect files.

like in the ending

Spoiler

you have to delete some files in order to complete the game
and i was wondering how to we do that?

your help would be much appreciated

You might be able to use System.IO namespace to do file operations, but Unity also provide a class to do some file operations on windows: Unity - Scripting API: File