Re: UEFI Secure Boot. Can it be deleted so to install "just" Linux?
No, uefi has replaced bios, but on most systems it can be disabled. Then the system can be installed in legacy(bios) mode.
Some OEM's implementation make that simple, others more difficult.
There may be some hoops to jump through depending of formatting of HDD, and boot loaders.
For the most part success can be had but some research and planning may be needed.
I know it's not the answer you were looking for, but there is quite a bit of information on this forum.
My best advice is to do your due diligence before buying your hardware.
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