What if I don't want to use iCloud Drive at all?

When we had a new hard drive put into our laptop, the Apple service we took it to installed High Sierra onto it. And all of the documents, as well as the desktop, were automatically moved to iCloud Drive. We never had a chance to say "no" to this move.

We don't want to use iCloud Drive at all. I rarely share documents or pictures between our devices; and the few times when I do, I use Dropbox, and then take them out again as soon as I'm finished. I don't want anything permanently stored in any cloud-based storage system because I don't want our stuff where it can be hacked. And in addition, I use the Desktop for manipulating files, and I don't like having a file folder that I dragged onto the desktop suddenly disappearing into the cloud. But I keep getting reminded that if I get rid of iCloud, I'll lose everything that the computer (without my say-so) has stored there. How do I get my Documents and Desktop folders out of iCloud Drive and back onto my laptop where they belong without losing it all? I don't need the cloud storage space; the hard drive on my laptop has plenty of room for what got moved out.