remove wordpress admin bar items from wordpress dashboard without plugin code example

Example 1: remove admin bar wordpress front end

/* Disable WordPress Admin Bar for all users */
add_filter( 'show_admin_bar', '__return_false' );

Example 2: wordpress remove all dashboard widgets

// Main column (left): 
// Browser Update Required
$wp_meta_boxes['dashboard']['normal']['high']['dashboard_browser_nag']; 
// PHP Update Required
$wp_meta_boxes['dashboard']['normal']['high']['dashboard_php_nag']; 
 
// At a Glance
$wp_meta_boxes['dashboard']['normal']['core']['dashboard_right_now'];
// Right Now
$wp_meta_boxes['dashboard']['normal']['core']['network_dashboard_right_now'];
// Activity
$wp_meta_boxes['dashboard']['normal']['core']['dashboard_activity'];
// Site Health Status
$wp_meta_boxes['dashboard']['normal']['core']['health_check_status'];
 
// Side Column (right): 
// WordPress Events and News
$wp_meta_boxes['dashboard']['side']['core']['dashboard_primary'];
// Quick Draft, Your Recent Drafts
$wp_meta_boxes['dashboard']['side']['core']['dashboard_quick_press'];