Did you try:
virsh undefine domain-id
where domain-id is your vm name
Perfect, thanks Earl! Here's the script in case anyone else might find it useful. Please post any improvements if you can see a way to improve it.
#!/bin/bash # Removes all KVM virtual machines from this host
# First destroy all running VMs for i in $(virsh -q list | awk '{ print $2 }'); do virsh destroy $i; virsh undefine $i; done;
# Next we delete their virtual disk images rm -rf /var/lib/libvirt/images/*.img