reinstall promox

Hi Guys, I am very new here and to proxmox. I am trying to learn proxmox and i tried to reinstall proxmox as the ip i assigned early has a conflict. But after re-install, i am getting grub error saying LVM is not available. after reading in google, i am able to login to my proxmox using the...

so i wanna reinstall my promox from usb, but when i boot into Bios i keep getting into GNU GRUB, cant i just go back the the normal bios i had before installing proxmox?