Just a long shot... but maybe partedUtil can help you out a bit.
First you will need to find the device:
esxcli storage core device list
Then you could try:
partedUtil delete <diskName> <partNum>
(e.g. partedUtil delete /dev/disks/naa.60001234567890 1)
If it is seen in /dev/disks then try to delete it using:
# dd if=/dev/zero of=/vmfs/devices/disks/<naa.###> bs=1M count=50 conv=notrunc
# partedUtil mklabel /vmfs/devices/disks/<naa.###> msdos
If it can't write to it then it could be in a Read-only state due to a hardware failure (it should state this when trying to overwrite and/or in vmkernel.log at this time).
Thanks to all those who replied and thanks to the Bobkin who has been really helpful in this post and in others
I managed to reach out to GSS
We rebooted the host in question and disabled the vsan services on boot
He logged back into the host and removed the disk without any of the vsan services running
Thanks again to the community here