Lxc delete fails with `dataset busy`

it seems my virtual machine disk got full while installing snap package (microk8s) and machine froze.
lxc ls reported as machine being frozen
trying to start it caused this

lxc start vmk8s    
Error: mkdir /var/snap/lxd/common/lxd/virtual-machines/vmk8s/config: no space left on device
Try `lxc info --show-log vmk8s` for more info

I thought: ok let’s delete that one and make one with more disk space.
So I tried to deleted it, but…

lxc delete vmk8s
Error: Error deleting storage volume: Failed to run: zfs destroy -r default/virtual-machines/vmk8s.block: cannot destroy 'default/virtual-machines/vmk8s.block': dataset is busy

what I need now is a safe process to remove it.
please advise

The block being active suggests that it may still be a leftover qemu process running?

ps aux | grep qemu?

yes, that’s correct, after killing the qemu initiated by lxd, everything went back to normal.