macOS (nee OS X) has a very handy print workflow automation feature that appears in the bottom left corner of the Print dialog.
Unfortunately, when you choose the Edit option, the only items you can remove are the ones that you have personally added. (That's a whole different post!) If you want to remove the ones provided by the system, it's not obvious how to do so.
In my case, I wanted to eliminate the "Save to Web Receipts" option. (Because I already have my workflow for that, which is the "Orders" choice you see in the screenshot.)
The answer: In order to remove the options that the UI doesn't let you touch, go to the folder /Library/PDF Services and delete the workflow or folder aliases you find there. (Doing so removes them for all user accounts, by the way.)
You may want to bookmark this post as macOS updates may add them back.
Update 2021:: Sadly, with the sealed System volume in Big Sur, it is no longer possible to remove some of these menu items. Please complain to Apple, I have!