Maybe I’m missing something, but is there an easier way to kill a task running on a slave other than restarting the slave or searching for the task in the task list? Like maybe something in the right-click context menu for the slave?
You must be in Super User mode.
Right-click the Slave in the Slaves panel, select Remote Control, then “Cancel Current Tasks”.
This will send a remote command to cancel all tasks of that Slave (for example if running Concurrent tasks).
Oh man, it was right there the whole time! I can’t believe I’ve never seen it. 
Thanks!