Trouble downgrading from Catalina
I'm trying to downgrade a computer from Catalina to it's original OS, Sierra, because Catalina made my work impossible. However when I go through MacOS Recovery, Mac HD - Data is available but Mac HD is unselectable and when I click it it says "You can't upgrade this version of macOS because a newer version is installed. That is precisely the problem. I'm trying to downgrade from Catalina. What gives? How do I get out of this Catalina **** and back to an OS that is compatible with my hardware?
iMac Pro