Assuming you're using vSphere 5.x/6.x, check the following VMware KB article: How to unmount a LUN or detach a datastore device from ESXi hosts (2004605) | VMware KB
About your steps, the number #1 is OK, but number #2 and #3 seems confusing.
Assuming you're using vSphere 5.x/6.x, check the following VMware KB article: How to unmount a LUN or detach a datastore device from ESXi hosts (2004605) | VMware KB
About your steps, the number #1 is OK, but number #2 and #3 seems confusing.