Allow Public Community Folders and Files with restricted access

HR department maintains a public community for employee information. Each year, some information such as health insurance coverage change so instead of replacing or deleting the files, they create an "archive" folder for that specific year within the community. They then post the current year files in a folder for the current year.

They did not want to delete the previous year's information (for referral purposes) but they would like to hide it from all employees by changing the access from Public to just members of the HR department for particular folders and files. Right now they have to create a new Community and move the folders and files.