This plugin disables the visual editor for all users across the whole site. You could also remove the wp-includes/js/tinymce/ directory.
This plugin disables the visual editor for all users, every time a user updates their profile. This means even if a user checks the box "User visual editor", the setting will not be saved.
To completely remove the visual editor, delete or rename the wp-includes/js/tinymce/ directory. This will remove the "Use visual editor" checkbox on user's profile pages and ensure that the visual editor cannot be loaded. Please note that you will need to delete or rename this directory after every WordPress upgrade.