If you get “permission denied” trying to delete printers, delete everything relevant in all of these places (leaving the folders of course):
HKEY_CURRENT_USER\Printers\Connections HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Devices HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\PrinterPorts HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows NT\Printers\PushedPrinterConnectionStore\* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Print\Connections HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Printers
restart the spooler, refresh the Devices and Printers window, and you may be done, the involved printers will probably vanish. If they don’t they will be deletable at this point. If there are multiple user profiles on the PC, you will have to delete them in the other profiles. On some machines, some of the folders won’t exist, and this is perfectly fine.