Replaced the standard drive in a fusion set up:

I asked this question last september and wondered if there are any new solutions.

Swapped a drives in a fusion set up

My iMac is set up using a SSD drive and a HD as a fusion drive set up.

I had a 1 TB HD Drive in my iMac. Part of diagnosing a problem I bought a new 2TB HD and put that in my iMac. It was an easy fix, it automatically fixed it to the new fusion set up. My question is I bought an enclosure for my older 1 TB HD and I can't see to erase it. When you hook it up it wants to "fix" it to link it to my system. I just want to erase it so I can use it as back up storage. Thank You for any help.