Ineradicable EFI boot entry

Greetings,

I'm looking around for another distro to try, because the complexity of Gentoo 
keeps increasing and I'm not getting any younger.

I found opensuse, and remembered that SuSE was my first venture into Linux, so 
I gave it a go. Mistake number 1 (today, that is).

The problem is that it's changed its way of maintaining the system, and it's 
all smoke and mirrors to me, so it's now gone - except that I can't remove its 
EFI boot entry with efibootmgr. The EFI BIOS has settings for secureboot, 
Intell platform protection, and admin and user passwords. I've cleared all 
those, even run 'dd if=/dev/zero of=/dev/nvme0n1p1' from a rescue system. 
Nothing has erased the opensuse entry.

Ideas, anyone?

-- 
Regards,
Peter.