I'm using spacemacs and tried to turn off company mode in org mode while keeping it in other major modes. I've tried the following:
(global-company-mode '(not org-mode))
but it's not working.
At the Spacemacs configuration layer level you can disable auto-completion layer for a set of layers with the following line in dotspacemacs-configuration-layers
(for instance disabling auto-completion for both org and git)
(auto-completion :disabled-for org git)