With the AODocs Smartbar installed, a library administrators can prevent users from modifying the sharing permissions of files and subfolders. To do this, go to the “Settings” (1) icon in the Team or Secured Folder and click on “Library settings” (2).
Learn more here: Install the AODocs Smartbar
Accessing Team or Secured Folder settings from Drive
Under “Security” (3), make sure that the “Only administrators can share files and folders” button is checked (4). Then, click on "Done" to save (5).
Allowing permissions to be changed at the subfolder and file levels
Note that the modification can take some time to be applied since AODocs will need to update the Google Drive permissions on every file of the Team Folder or Secured Folder. For a Team Folder or Secured Folder with thousands of documents, it can take several hours before the change is fully applied.