You can prevent a specific Security Role from creating Root Folders.
To access this setting:
Go to the Setup Home Page.
On the left sidebar, go to Security > Security Roles.
Click on the Role for which you want to configure this setting.
Under the All Entities tab, find the “Folder (system)” entity and click Change to its right.
Click on the Folder Settings tab.
Under Advanced Permissions, uncheck the Create Root Folder box.