How to Hide the "L47 Audio Player" Admin Menu

function plt_hide_l47_audio_player_for_google_drive_menus() {
	//Hide the "Settings → L47 Audio Player" menu.
	remove_submenu_page('options-general.php', 'l47ap-settings');
}

add_action('admin_menu', 'plt_hide_l47_audio_player_for_google_drive_menus', 11);

Where do I put this code?