Do you have "Bring Your Own Device" policies currently in place? Even though the work on the computer started before the policies may have been in place, you w

Do you have "Bring Your Own Device" policies currently in place? Even though the work on the computer started before the policies may have been in place, you would be able to enforce a device wipe or clean-up with those procedures. Your next best option would be an NDA, since legally you could pursue action if they did use the system against you or for their own benefit. Technically, ignorance of policy doesn't excuse actions; that excuse flies like a lead balloon in court. The other question might be, why are you letting go of a seasoned member of your team? If there is someone their junior then why not them, or check with the person you're looking at letting go and see if they'd be willing to take a pay cut to stay part of the team (assuming it's payroll related and not behavioural). Lastly, if it's PII, the legal ramifications for the employee should be enough of a deterrent that they wouldn't go about disclosing the information in a manner that could be tied to them, and most people don't have and can't find the connections to "sell" the data.