I have Ubuntu 19.04 that I would like to get rid of completely and install 20.04. Doing the standard upgrade cycle of upping to 19.10 fails with "Doing an upgrade from 'disco' to 'focal' is not supported with this tool".
Editing the BIOS to boot from a USB drive boots into the old 19.04 version.

Coming from the MS world what are my options, short of cleaning the hard drive ?

if you want to remove it completely you can download a 20.04 install image and run it from a pendrive (make a full install).

Thanks for your reply but that's exactly what I did. Sorry if I wasn't clear but the box would not boot from the USB drive no matter how many times I edited the BIOS.
After some more research I found the problem. The motherboard is an earlier generation Intel Desktop server board and the BIOS editor had three separate entrt points at F2, F7, and F10. Even though the standard F2 menu had a boot priority function it would always boot from the hard disk. What I missed was that the F10 entry point - because it flashed by so fast during POST - was the boot menu where it was possible to change the boot device order.

does it mean you could finally boot from usb?

Yes.

so please mark the thread solved.

Being an LQ noob what's the protocol for marking it as solved ?

It is at the top in the thread tools option you can mark as solved, if my memory serves me from the other day. And looking at the thread that told me how to do it that is correct.

https://www.linuxquestions.org/quest...ml#post6163576