I'm having the same problem. There is no mod folder to delete. I got it from the in game mod library. I have been though every Factorio folder on my computer and even did a computer wide search for it and got nothing.

I just installed a bunch of mods via the in game mod library, and now I cant get in the game. one of the mods I installed is "nil" and I cant remove it since its from the in game mod library and not a manual install how do I by pass or remove the bad mad? I tried uninstalling and reinstall...