The commands for controlling menus work on menus even if the specified menu isn’t showing in the menu bar, either because it isn’t available at the current user level or because it has been toggled by the Paint tools. You can, for example, disable the Patterns menu even while using the Browse tool.
Once a menu item has been removed from the menubar by the delete command, you can no longer operate on it with HyperTalk. You must use the reset menubar command to return to the standard HyperCard 2.0 menu, or recreate the menu with the append command.