In order to remove a monitored item, you have to expand the list under the node in Node Management and delete from there. I would like to request that if you hit List Resources, that it would show include all items listed under Manage Nodes so we can remove unwanted items from the List Resources tab as well. I have this issue with LUNS/volumes that have been removed from the server that are still being monitored. Showing the status (i.e. UNKNOWN / or size of volume) in the list would be helpful for targeting what to delete.
It's confusing that you cannot manage everything from List Resources for a node.