There are many ways to do this:
One way is to kill the OneNote Launcher, (it sits in the taskbar and listen to the HotKey) or you can remove it from the running at Startup. (Press Win+r and type
msconfig
and go to Startup tab)Using AutoHotkey, you can get back your Hotkey to do anything of your choice by placing the path to the desired program:
#n::Run <Path to the executable>