Best way to remove items that are "assigned" to something else?

Question

I'll try to explain what I mean by "assigned"...

I have a site for managing a restaurant. In one section, I have a page that lists out all the restaurant inventory. In another section, they can manage the menu by assigning inventory items to a menu item.

There is a global inventory list that the restaurant can add inventory from, the global list contains nearly every food ingredient imaginable. Creating the UI to add from the global list was easy enough, just create a checkbox list separated out into categories, and let them choose what they want to add.

My problem comes from when they want to remove an inventory item for their restaurant that is already assigned to a menu item. How should this be handled?

Should there just be a message saying "Please remove this item from the menu before deleting?", or maybe something saying "If you confirm you want to delete this inventory item, it will be removed from these menu items:"? Or something else entirely I'm not thinking of?

Answer 1

My counter question would be: Is it even POSSIBLE to remove inventory items when they are still attached to a menu? Will the now-no-longer-complete menus break?

Considering this, I'd take the second approach (confirmation), since users will understand the impact. I'd maybe list the menus that will get affected.

In the list of menus, I'd include a small hint that from now on shows that the menu is now "incomplete", thus has not all ingredients it needs, so everyone has a clear overview on if a menu can be cooked or not.