How to Hide the "User Name" Admin Menu

function plt_hide_cas_username_display_custom_shortcode_menus() {
	//Hide the "User Name" menu.
	remove_menu_page('casusdic-settings');
}

add_action('admin_menu', 'plt_hide_cas_username_display_custom_shortcode_menus', 11);

Where do I put this code?