I’ve cleared entries before with efibootmgr.

deleted by creator

I’ve done this recently twice and it worked between 2 different distros on different hardware. I don’t remember if I had to link it again, but if I did, it worked and my history was intact.

If by ”backup” you mean “infrequently used”, be careful about using Tutanota for that purpose - it will delete free accounts after 6 months of inactivity.