This is normal. You have to uninstall 1st the previous nvidia config (video-nvidia-prime-render-offload). Then install the right one.
You should have used the Auto-install proprietary drivers button. Selecting the wrong one manually created all this mess.
Use the terminal
sudo mhwd -r pci video-nvidia-prime-render-offload
sudo mhwd -i pci hybrid-intel-nvidia-390xx-dkms-bumblebee
Read usage instructions
mhwd -h