Hi ,
Can you please let me know if I can kill any existing jobs running .I made changes to query and I am not able to revert back or kill the existing running session .
Killing the Workbench service in Task Manger or in Services should stop it from running.
You'll want to both kill the Workbench process and restart the Workbench service in services to make sure it's no longer running and attempting to process your data.
If that won't work then there's always the Windows solution - reboot the server.