Root Item class is Public by default?

Summary:

Is it Root Item class is Public by Default? Can we change it to private, Because I am not able to add any Security role to Root item class

Content (required):

Is it Root Item class is Public by Default? Can we change it to private, Because I am not able to add any Security role to Root item class

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

23B

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