When you turn off or remove the My Account link in the Navigation editor, it now disappears from your public site right away, on both the desktop menu and the mobile menu, as well as your footer links. You no longer need to click Save navigation or keep the editor open for the change to take effect.
If you turn My Account back on, it returns just like before: customers and visitors see My Account, and your staff see Dashboard. Menus that never included the link keep it hidden.