You keep your files safe by having backups. Multiple copies. Set up the backups to gets copied to another server or other system your regular user doesn’t have access to. Ideally, you follow the 3-2-1 backup standard if the files are important. That is 3 copies, on 2 different media, and 1 offsite. There are many ways of accomplishing that and its up to you to figure out what works best.