Customer Classification Category - Allow Parent Code Assignment

Summary:

Customer Classification Category - Allow Parent Code Assignment

Content (please ensure you mask any confidential information):

Classification Category created without enabling Allow Parent Code Assignment flag. Now when tried to edit category , this flag is not editable
1)How to enable it now?
2)What's the real use of this flag , can we continue using category without enabling it?

Version (include the version you are using, if applicable):

25C

Code Snippet (add any code snippets that support your topic, if applicable):