Hi, good day!
I recommend creating a USB Installation media and booting from it as if you were doing a Clean Install of Windows.
Under Windows Setup, select Custom: Install Windows only (advanced)
Select each Partition in the list then click Delete until it shows Unallocated Space
Once Done, turn it off then ship it to Dell for recycle
I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed.