The same way you protect those network drives from an employee accidentally or intentionally deleting everything.
Limited permissions work, backups work, journaling data storage systems with an ability to rollback all changes work.
In most environments nowadays I guess there's no valid reason to have a literal "network drive" - if your users don't need to wrangle terabyte-sized data blobs, most environments can afford the overhead to have the company document/file sharing to happen in some system that stores full history of changes, and where normal users can not remove that history even if they're malicious or infected with malware. Probably even Dropbox or its competitors would be sufficient for that, no need to go to the more enterprisy vendors.
Limited permissions work, backups work, journaling data storage systems with an ability to rollback all changes work.
In most environments nowadays I guess there's no valid reason to have a literal "network drive" - if your users don't need to wrangle terabyte-sized data blobs, most environments can afford the overhead to have the company document/file sharing to happen in some system that stores full history of changes, and where normal users can not remove that history even if they're malicious or infected with malware. Probably even Dropbox or its competitors would be sufficient for that, no need to go to the more enterprisy vendors.