This document explains how to completely remove printers from Windows.
1. Open the command prompt (click start, type CMD on the run line)
2. Right-click on the shortcut, "Run as Administrator"
3. Run the printui tool: printui /s /t2
4. Try deleting the printers. If that doesn't work...
5. Click Start > Run > Services.msc
6. Locate the Print Spooler service, and right-click > Properties > stop service.
7. Open My Computer and browse to c:\Windows\System32\spool\Printers
(you will need to say "OK" to get access to the folder).
8. DELETE the contents of that folder.
9. Restart the computer