I managed to mess up my USB installation medium tonight… managed to turn it into a NTFS, read-only USB, so I couldn’t delete anything.
Since I just wanted to delete everything, I just wiped the drive using
parted, downloaded the iso, and copied it using
parted \dev\sdb (parted) mklabel gpt (parted) mkpart 0% 100%
Then download an iso from one of the online repositories. Suppose we place it in
~/archlinux.iso. The command to copy the image onto the USB is:
sudo dd bs=4M if=~/archlinux.iso of=/dev/sdb status=progress oflag=sync