uninstalling linux lite from terminal

[Moltke]

I changed the boot priority in Bios but it just seems to default to linux every time or that grub menu.

Hmmm... What options are available in boot priority? There should be 3 at least; internal HDD, USB and network. Is it UEFI or Legacy BIOS? Did you choose USB? What option did you choose? If UEFI, you have to change the UEFI boot order too, it probably is set to boot from internal HDD so change it to boot from USB/CD-ROM drive.