By default employee users have access to upload documents. If you don't want employees to be able to do this, you can control this within your Documents settings.
Click your name in the top right-hand corner, then click Settings.
On the General settings menu, click Employee data.
Click Documents.
Scroll down, then either select or de-select Allow employees to upload documents.
Click Save.
Now only admins, direct managers and team managers can upload documents.