There is an extra section at the very bottom of the website backend

Hello,

That area bounded by the red rectangle with the + folder is not a page layout section or Flexbox element—it is the Elementor Drag & Drop Add Zone (the canvas placeholder).

Here is why you cannot select or delete it:

It is a built-in editor feature: That area is built directly into Elementor to allow you to add new containers and template blocks to the bottom of your page.

It does not render on the live website: It only appears inside the backend editor. Visitors will never see it.

It is dynamically created: Because it isn’t an actual structural container, it will not appear in the Navigator tree on the right, and it cannot be right-clicked or deleted.

Best Regards