Intel Mac Fusion Drive Erase and reinstall Mac OS
I have an older Mac that I wanted to send back to apple. I am trying to erase the drive and re-install Catalina. I have done this several times using Disk utility. The process seems to be successful but when I go through the set up and check About this Mac>Storage there is now another hard drive. I think the original computer had a Macintosh HD and Macintosh HD - Data. Somehow a Macintosh HD-Data-data was added. Since then I tried to erase and remove all the volumes shown in Disk utility and now am unable to install Catalina on AFPS since it is unable to add a Pre-boot volume.
My main question is, Did I actually erase the drive already? I was concerned since the new volume that showed up had "other volumes" with varying amounts of data that would change when I would try to delete and reinstall the OS. I only wanted to install Catalina so that the imac was working and I could get the $75 the computer is worth on trade in. I would rather forfeit the 75 and ensure the mac is clean of data. I know I made a mess of this on my own but I do appreciate any thoughts.