You might go into more detail as to the process being used to re-install Windows.  Normally, Bios changes are not required to do that.  If you started with a clean drive or removed the current partitions, at least the 4 primary partitions, the system should at least allow you to start the install. If you can't boot to a USB drive which contains the install media then perhaps the USB drive is not configured correctly.  You would normally see a UEFI version of that drive. Were you having a problem which needed your OS to be reinstalled?
I was trying to re-install windows 10 and managed to mess up the settings in the BIOS under BOOT SEQUENCE SETTINGS such that I now have no boot options ! When I go into the Boot Sequence menu I have nothing listed under Boot sequence.    Then under the Boot List Option I have UEFI selected and if I click on Add Boot Option I have 4 items in the file system list, each one starting PciRoot(0x0)/Pci(0x17.00x0)/Sata.....which means nothing to me. I am thinking to re-install the BIOS under the F12 menu. I'd be very grateful for assistance.  
DELL XPS 15 9560 NO BOOT OPTIONS