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add_action("admin_menu", function(){
remove_submenu_page( 'themes.php', 'themes.php' );
remove_submenu_page( 'themes.php', 'nav-menus.php' );
remove_submenu_page( 'themes.php', 'theme-editor.php' );
});
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// Hide WordPress admin bar
add_filter('show_admin_bar', '__return_false');