See this ubuntu appears in BIOS menu
I have this on my Lenovo s205 too.
Is there some way to remove "ubuntu" from the menu? I don't even have it installed anymore.
You should be able to do this via a Live Ubuntu CD.
Then add to the kernel efi support
Then delete the option you dont want. In this example, Ubuntu is entry 5. the following could be called to delete entry 5 and remove it from the BootOrder.
Further details described here: http://linux.die.net/man/8/efibootmgr
Note: as for anything that changes your bootloader, please ensure you have a good disk image that you can boot with.