Where can I unbind alt+m?

I've been using Alt+m as my toggle mute over discord, and I just realized it was causing my minimap to lock. I could never figure out what was causing my minimap to just stop functioning when i wanted to click on it to see what was going on in a fight, etc. How do I get rid of the bind? It isn't in the league client settings from what I can tell and also not in the persisted settings file.