WP-Mix

By default WordPress enables users to switch themes while working in the Admin area. Sometimes a user might screw this up and accidentally activate the wrong theme.

To prevent this, add the following code to your functions.php file:

function remove_theme_menus() {
	global $submenu;
	unset($submenu['themes.php'][5]);
	unset($submenu['themes.php'][15]);
}
add_action('admin_init', 'remove_theme_menus');

Technically theme switching will still be possible, but this code will prevent mistakes by disabling WordPress theme menus. Good times.