You will need to kill the follwoing virtualizor scripts running in the background on the source and the Master server to stop the migration/cloning process.
1. The shell script "migrate_dd.sh" responsible for "dd" running on the source server.
2. The migration script running on the source.
3. The Task script running on the Master.
You can find all the PIDs by executing ps aux | grep migrate .
Note : It is not recommended though as the task in the Admin panel would still be active as Virtualizor is unaware of the manual killing of the running scripts.
Older one but the best result from google when searching on the topic...
Following the previous answer, if you want to remove the orphaned lv, there are additional dd tasks running which can be discovered leveraging this answer:
https://serverfault.com/a/617692/551613
# dmsetup info -c | grep vol0
using the 2nd and 3rd column (major and minor), find the process to kill for the LV with
# lsof | grep "major,minor"