Disable raid precision 5820

Not possible because your Raid usually uses SAS drives not regular sata drives.

https://www.dell.com/support/kbdoc/en-us/000132392/

You can change from using the raid controller to using regular sata drives but its not a single step single reboot water chicken install.

The issue you are having is not knowing how to install F6 mass storage drivers for windows install.

https://www.dell.com/support/kbdoc/en-us/000148150

If you actually have SATA and Not SAS Drives and the SATA drives show up in F2 bios setup then you can set SATA OPERATION to AHCI.   Remove All drives EXCEPT FOR DRIVE 0.  And then install windows from an OEM Windows DVD by F12 booting from the DVD.

The DVD is very inexpensive and you dont need to do anything to create it.  It just works. You do not need a license it gets that from the bios.

https://www.newegg.com/microsoft-windows-10-pro-64-bit-reinstall-recovery-disc-only-no-license-key-included/p/N82E16832350238

So you likely need at least 1 sata cable and either a 2.5 inch SATA Laptop drive or a 3.5 inch SATA desktop Drive.

https://www.newegg.com/p/0ZF-00GH-00015

https://www.amazon.com/Seagate-Mobile-Laptop-Drive-128MB/dp/B01BVS75MK

My unit came with 2 SAS Drives and Raid controller using 2.5 inch drives.

I removed the Raid controller. Removed the sas drives.

Added a Blue Sata cable to DRIVE 0 on the motherboard.

Added a 2TB Sata Laptop drive and put that in the caddy where the SAS drives were.

Connected SATA power and Sata Data Blue Cable.

Then cleared CMOS and replaced CMOS battery with new one from the local store  Duracell DL2032.

Once that was done I F2 setup Bios for Drive 0 SATA AHCI on and then Made sure the Optical Drive was detected Drive 1.