My site is now frozen and I can't deactivate plugin

There is no trick to deactivation, just deactivate from the plugin list or manually delete (or rename) the plugin folder using FTP or your web host’s file manager. Code Freeze does not make any actual changes to your site and removing it by brute force if necessary will have no bad effects.

That said there was an issue where the previous version did not support plugin list deactivation in WP 3.7.1. I apologize for this and have fixed it in the updated version. Please note the versions the plugin supports fully at the time of install!