Hi Joh,
I found quite a few bits and pieces of VMs lying around when looking at
how to recover VMs from my previous install. This might take a while,
but you can run the following commands in a root terminal session on dom0:
# cd /
# grep -r <vmname> * 2>/dev/null
No guarantees, and be careful what you remove/edit, but it's worth a shot.
Ron