Now that the disks have been set up, they must be detached from the VM instances so that they can be used for the next step. The VM instance is deleted in the process.
In the Google Developers Console, click Compute > Compute Engine > VM instances > rhgs-primary-n01.
Scroll down to the Disks section (there should be one for the boot disk and one for the additional disks). Ensure that the checkbox delete boot disk when instance is deleted is unchecked and the option for When deleting instance is selected the additional disk shows Keep disk.
Now, click Delete on the top to delete the VM instance.