On win7 64 bit I found it under
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\hewlett-packard\DigitalImaging\HP Color LaserJet CM1015 PCL 6\DeviceInstances
My MFP is a CM1015, so yours would be a Photosmart. I had 2 entries under this,and once I deleted one it vanished from solution center as stated in above posts.