How to Hide Boxzilla Admin Menus

function plt_hide_boxzilla_menus() {
	//Hide "Boxzilla".
	remove_menu_page('edit.php?post_type=boxzilla-box');
	//Hide "Boxzilla → All Boxes".
	remove_submenu_page('edit.php?post_type=boxzilla-box', 'edit.php?post_type=boxzilla-box');
	//Hide "Boxzilla → Add New Box".
	remove_submenu_page('edit.php?post_type=boxzilla-box', 'post-new.php?post_type=boxzilla-box');
	//Hide "Boxzilla → Settings".
	remove_submenu_page('edit.php?post_type=boxzilla-box', 'boxzilla-settings');
	//Hide "Boxzilla → Extensions".
	remove_submenu_page('edit.php?post_type=boxzilla-box', 'boxzilla-extensions');
}

add_action('admin_menu', 'plt_hide_boxzilla_menus', 11);
Where do I put this code?