Provide some feedback to the user when a Backend is going to be deleted. The idea is to inform the user why the backend cannot be deleted (because it is used by products) and to provider the list of such products so that they can navigate to them.

For example:

• Disable the delete button and show instead a list of products used
• Before/After confirming deletion, show a popup with a list of products used

Suggestion:
Instead of a simple list, the popup could feature a slider for each product so that the user could "detach" each product from the backend.