The siteurl and home address are greyed out because they are defined in your wp-config.php file. Check if your wp-config.php file contains this:

define(‘WP_HOME’,’http://example.com’);
define(‘WP_SITEURL’,’http://example.com’);

The home and siteurl can also be hardcoded in the theme’s functions.php, you can check that as well. Click here for more information.