It is possible remove a cluster resource when the reource is online.
If you attempt to delete a cluster resource or clustered pool without first offlining the cluster resource, deletion errors occur, the data associated with the clustered pool is not recoverable and everything turn seriously complicates...
To avoid this problem, the cluster resource always must be offline.
It would be very useful that when you try to remove a cluster resource with iManager (or NSSMU), the NCS check the status of the resource and if this "Online", the resoure can´t removed and show a message informing that the resource is "Online". It might even offer the option of placing "Offline" to continue the process.

by: Carlos R. | over a year ago | Cluster Services (NCS)