If you want to delete all your data on PC version. you need to delete all your save file in your game folder and also your game data at %appdata%/renpy/lustfuldesire...
But if you just need to choose a choice in Nameless event again. You need to have older version of 'persistent file', one before you choose a choice.
Persistent file is a file which contain all game data in there, a dialogue you have been read, a choice you chosen, and yes, persistent file contain a choice you chosen in Nameless event too.
On PC version, persistent file will be in 2 folders, one in save folder which locate in game folder and another one in %appdata%/renpy/lustfuldesire .. In PC version you can replace older persistent file to current persistent file in both folder to remove a choice you have been choose. But you may have some risk with this because persistent file is very important file for a game, it may cause some bugs if you replace or remove it so please consider it carefully.
BTW if you don't have an older one, I can give you mine. If you want.