You can delete your research data unless a request has been made for it under FoI/EIR. Once a request has been made it becomes a criminal offence to delete or destroy the information. Most of the sanctions under this legislation apply to your institution, but any action for deletion or destruction could be taken against the individual who did it or ordered it! Don’t do it, and make sure it is not deleted accidentally after the request. A policy on managing research records can be helpful in demonstrating that data has been deleted to a pre-determined schedule, and not to avoid FoI requests.