New
#11
Yes, power down to open the case then pull the data or power plug on each of the other HD's except the target one.
You have illustrated tutorials for how to get a perfect reinstall, and how to wipe the HD first from the installer Command line accessed by pressing Shift + F10 at the first screen when booted.
If you have any questions you should ask back for immediate help. We have a 100% install rate for those who cooperate and interact closely to get the steps done.