Is there a way to cancel a job that is queued or running? Like starting a cloning task, and then wanting to stop it?

If you put in a ticket, someone /might/ be able to stop it. Otherwise, no.

Note that you can boot a node with a cloning occuring /from/ it - but the resulting clone will be corrupted. So you can boot up the source while waiting for someone to respond to your ticket and abort the job.