I recently got a new laser printer. The printer is connected to my desktop/server via USB cable and my laptop uses it via CUPS. (I use Ubuntu 22.04.3.) I removed the old printer from the list of available printers on both the server and the laptop. The old printer kept reappearing on the laptop’s list but not on the server’s list.
Someone once wrote “Everything in Linux is a file” so I decided to search for the file that contained the list of available printers. In the directory /etc/cups/ppd there are .ppd files for each printer. Deleting the one that referred to the old printer and re-booting fixed the problem.
I don’t know why removing the old printer via the Printers page in Settings didn’t work. Possibly it was a permissions issue. I also don’t know if there are other locations that still have configuration information for the old printer but so far there have been no issues arising from my deletion of that .ppd file.