... and, if you want to figure out the batch requestor id that is running this job, then -
From admin studio locate that job and initiate trace.
As soon as tracing actually starts, stop the tracking.
At the top of tracer window, the requestor id can be found.
if the job is enabled on multiple nodes, you need to repeat these steps on such remaining nodes.
Please note that if you planning to stop a job abruptly in an environment like Production, first verify that by terminating that job mid way will not cause data loss or data corruption. If there is a chance, my suggest would be wait the job run out, as that would be a safer approach.