Cannot Remove HP Universal Printing Printing, Cannot, Remove, Universal

yangcctv

Hello, I have two Windows 2008 Citrix XenApp 5.0 servers. I am trying to uninstall all traces of the HP Universal Printing drivers that were installed on them by accident (PCL 5 and PS). Whenever I attempt to remove the drivers under the Print Server properties, it tells me the drivers are still in use. I get that same message even if only the administrator is logge in and all the printers were deleted. How can I completely uninstall them?

Thanks,
John