Edit Windows UEFI boot entry using windows PE

To be able to edit the boot settings you need to be able to boot from another boot device like USB stick or CD. You need to create a bootable WinPE boot media first
When you have started the WinPE (this should work starting with WinPE for Windows 7) environment open a command line and start a command prompt. First you need to mount the EFI system partition:

# diskpart
# list disk
# sel disk 0
# list partition
# assign letter=b
# exit

Now the EFI system partition should be as drive b:.

In the next step you can start to edit you BCD entry:

# bcedit /store b:/efi/microsoft/boot/bcd /enum
# bcedit /store b:/efi/microsoft/boot/bcd /deletevalue {default} safeboot

In this example a safeboot entry would be deleted from the store.