All I can offer is suggestions.
1] Disconnect the existing printer whilst the computer is turned off. Boot up, see if you can now delete the phantom printer.
2] Boot into Safe Mode and see if you can delete the phantom printer.
3] See if the solution found by the OP himself in the thread below works for you;
4] Disconnect the existing printer, boot up and uninstall that printer. See if that allows the phantom entry to be removed. But only do that if you still have the software for the HP 4300, and follow the instructions for reinstalling that software afterwards.
Not much help am I?
On my husband's Win7 64 bit machine I have an extra printer listed (don't know how it got there) it says it's a HP printer. I have a HP 4300 printer that's good. The stray one has a yellow exclaimation point on it and I can't troubleshoot it because it doesn't exist. And there is no remove printer choice on it. How do I get rid of it?