The exception appears to be due to http://jira.jboss.com/jira/browse/EJBTHREE-581 . It keeps happening over and over because the eviction algorithm keep retrying the eviction.
However, I don't see how this would prevent undeployment of the farmed EJB. The way to remove the farmed deployment is to remove the deployment unit (e.g. tutorial.jar) from the farm directory on a running node. Sounds like that's what you did.
What exactly did it say on the other server?