Let me guess, you have security concerns about leaving sensitive info on the HD?
If that is the case then you should consider switching to a pull print solution. Something where the print jobs are not stored locally on the printer at all but instead stored on a server that you can harden and monitor more closely. That way the printer only has to stream print info and store it in RAM until its ready to print. The RAM gets overwritten frequently and deleted when the printer is powered down.
That being said opperating a printer without a HD is not likely going to work for you. The printer is going to complain about a missing or malfunctioning component every time you boot or whenver there is an error. It would be much easier to simply let folks use the printer as it was intended and then take a hammer/drill/shotgun to the HD when you are done with it.