Navigate to your company settings in the top right corner and open the Permissions tab.
The first list of options you will find are manager settings. Here, you can select whether managers can view and add files for the staff they manage. Click enable editing to turn this setting on and off using the tick box.
The second list of options you will find are your staff permissions.
Here, you can select whether staff can upload files to the company files page.
Untick this box if you would not like them to have this ability.