Hi @olivierlambert ,
Okay, I made some progress today and have worked out the steps to remove, delete or add drives to a VM.
Removed drive from the server attached to and also deleted the disk itself
xo-cli vdi.delete id=<the id of the VDI>
Removed drive from the server attached to, but didn't delete the disk!
xo-cli vdb.delete id=<the id of the VBD>
Added a drive to the server
xo-cli vm.attachDisk vdi=<the id of the VDI> vm=<the id of VM>
If was the last one that I was missing. I'm still not sure of the difference between the 'uuid' and 'id' fields, but will use the 'id' as this seems to be what the commands are wanting.
Thanks
Kent.