Disable New Subfolder option : how to?

Dear members,

I'm trying to find out how to disable the New Subfolder option in the Folder tree,
without using the config file.

I need to do it on initializing the cfkinder. I managed to disable some functions on file level using :

finder.callback = function( api ){
   api.disableFileContextMenuOption( 'deleteFile', false );
}

But I can't find the right command to disable features on folder level.
Can anyone point me the right direction, please? tx!