That is not what I mean. It is in BIOS. Not Windows bootloader. Ubuntu was installed through UEFI. The problem here is that BIOS finds "ubuntu" UEFI partition from hard disk. Ubuntu is not on hard disk, the system is not installed, the bootloader of it is not on computer. Just this UEFI partition. I can't get rid of it. It really annoys me, and I'm thinking is DBAN the only solution here (that should delete ALL, EVERYTHING! from HDD, right?)
More information is that Windows 7 is installed through UEFI too, so BIOS has "Windows Boot Manager" and "ubuntu", and trying to boot that ubuntu doesn't do anything as it does not exist. The problem is that I havent found a way to delete the UEFI partition of it.
So let me explain:
Windows is not asking do I want to boot Ubuntu or Windows, there are no other than partitions of Windows.
Only an UEFI partition probably is stored in HDD, and nothing can get rid of it, and BIOS sees an useless boot option (trying to boot this ubuntu does nothing as the system doesnt exist, PC continues to next thing in boot order)
So, this is not anything serious, it is just that UEFI partition, nothing else, it wont ruin my life, wont annoy me in system, it is just an UEFI partition which is useless.