How to disable secure boot for AN515

Ninpodeshi

I'm thoroughly unimpressed & disgusted with Win10 and want to install Linux on an SSD drive that I just had installed.  I made a bootable USB with Rufus (MBR, FAT, ISO; the fist time I chose GPT, NTFS, ISO & it didn't recognize the USB so I rewrote it to the preceding).  It will begin to load the drive, but all I get is constant error messages.  I've been told to disable the Secure Boot feature in BIOS, but BIOS will not let me change that setting.  Any help would be appreciated.  Thank you.

Model: AN515-42

OS: Win10 single language 64bit

BIOS: v 1.08

CPU: AMD Ryzen 2500U

Graphics: Radeon Rx 560x

Graphics 2: AMD Radeon Vega 8 Graphics

ven98

Create a supervisor password in BIOS and that will enable you to change the secure boot option.