Each system is different, but the basics are:
1) Backup your data (as this will wipe everything from the hard drive)
2) Reset the system BIOS/UEFI to default values and check to see if it's in UEFI or in Legacy.
3) If in Legacy, go into the BIOS and manually change it to UEFI and ensure that Secure Boot is also selected.
4) Then boot from the manufacturer's restore disk (or the Windows disk) and install Windows from there.