Hello,
Yes. So you can't just remove a menu item alias. The menu item's are the entire structure of your site and they follow the path they are built.
If you add an item to it and don't want the parent alias then you need to add the item to the same level as the parent and set the display options to hide. Then add a menu item type 'Menu Item Link' to link to the menu item you created.
Many thanks
tony