I had some spare time so I tackled the problem of uninstalling the Transporter Desktop.
First step, I reinstalled it. This time, I got a complaint from the OS that the app came from an untrusted developer and my settings would not allow me to run it. This is very strange. It didn't tell me this a few weeks ago when I first installed it.
I found the Security settings and told it to allow software from everyone. Then I could run the Desktop. I set it up again per instructions. Unfortunately, it renamed my hard disk from "Macintosh HD" to "f?". This started to disturb me. Had I unwittingly got a malware version of the Desktop?
Then I went to the support website again and downloaded the Uninstall App. It ran this time, probably because I had changed the settings to allow any software to run, not just from Apple or trusted developers. It asked a few questions, and then it removed itself cleanly. Everything went - Desktop, drivers, everything. And it rebooted.
Then I had to work out how to rename my hard disk back. Quick Google showed me, and a few seconds later it was all back to where it should be. I changed the security settings back to only allow Trusted Developers to run software. It might be Nanny State, but I'll leave it on. I don't do anything much on this Mac Mini, just manage my Drobo, so I don't need to run all sorts of things on it.