Booting from usb with Qubes installed


I have installed Qubes as the base OS on an Acer Swift 3. I’m fairly new to Linux and I realised Qubes is overkill for want I really want to do.

I have since tried to create a fresh ubuntu install however I cannot get my PC to boot from the usb. In the Bios the only boot option is Qubes.

I have looked at Grub and it seems to only give me options for the hard disk. Listing (hd0) (hd0,gpt1), (hd0,gpt2), (hd0,gpt3) with ls.

Does anyone have any sugestions on how I might be able to remove or overwrite my qubes installation?

Thank you,

With the instructions from that post I was able to install Ubunutu over qubes.