You can restrict folders and albums of your choosing using the Permissions function.
Note: All assets in the folder or album you are restricting will be restricted and removed if the assets are housed in another folder or album.
To do so:
1) Go to any folder or album in your Library
2) Once selected, click on the View Detail information icon.
3) You will see the Permission function.
Here, you will be able to define who can see which folders and albums. You may choose between a specific user and group.