Disable the ability to delete the configuration scheme while configuring custom field

At the moment, it's not possible to disable the option to delete the scheme while configuring a custom field. So user would easily delete the scheme unintentionally which make it hard to maintain data consistency.

It would be a "nice to have" feature to be able to disable the option to delete the whole scheme with one button to avoid the scenario mentioned above. Alternatively, a warning message should be displayed on the page to avoid the user to delete it accidentally.