So I just started to speedrun this game and I went into options to turn off Submitting scores and I did and it still submits them. Am I doing something wrong?

You need to play in offline mode.

In other words, turn Steam to offline mode before launching N++.

Assuming you are on windows. You can add an firewall rule that disables the N++ executable from accessing the internet. Offline steam works as well but you don't have to remember to do it and it only effects N++.

There is also an option in game btw

That option makes the game submit individual level scores when playing in episode mode. If you turn it off episode scores are still submitted unless you're in offline mode.