If you have installed the nodes in a Rocks Cluster and now you want to remove any node, you can easily remove the node by using insert-ethers --remove command.
Let's consider you have to remove the following nodes
and c) compute-0-2
Then you can remove it using the following commands
# insert-ethers --remove="compute-0-0"
# insert-ethers --remove="compute-0-1"
# insert-ethers --remove="compute-0-2"
After removing the nodes you again reinstall the compute node by booting it. This way you should be able to install the compute node correctly.
Recommend the tutorial