All you have to do is simply paste the following code in your theme’s functions.php file. Although it maybe a good idea to save this file as a plugin and make it a drop-in plugin.
Info
function remove_dashboard_widgets() {
global $wp_meta_boxes;
unset($wp_meta_boxes['dashboard']['side']['core']['dashboard_quick_press']);
unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_incoming_links']);
unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_right_now']);
unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_plugins']);
unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_recent_drafts']);
unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_recent_comments']);
unset($wp_meta_boxes['dashboard']['side']['core']['dashboard_primary']);
unset($wp_meta_boxes['dashboard']['side']['core']['dashboard_secondary']);
}
add_action('wp_dashboard_setup', 'remove_dashboard_widgets' );