The LUNs on the old pool still exist. So unmount the datastores in vCenter, remove the LUNs from the storage group and then delete those LUNs
  Hi   I have recently created a new Storage Pool to resolve the capacity issues on another Storage Pool. The LUNs on the original Storage Pool were all allocate to VSphere.    Although I have moved VM servers from LUNs in the original Pool to LUNs in the new Pool, the physical capacity (% full) has remained the same.  Is there anything else I should do to reduce the physical capacity of this Pool?    Thanks  
Storage Pool - reducing physical capacity