You have turned off your objects in the viewport however it is still showing up in the rendered image. This is not a bug or an issue, it’s because Blender 2.8 have separated viability options for the viewport and rendering. The rendering visibility is hidden on the default setup.

1. Open Filter panel from the Outliner and switch on the Rendering icon (Camera icon)

2. From Outliner, hide your objects by click on the Camera icon. Now the objects is hidden from your rendered image. (Note: switching off the viewport objects (eye icon) does not effect the rendering image)

3. Render > [...]