You enable the BuddyPress Social Features you want to use when you run the installation wizard when instaling BuddyPress.

You can selectively enable or disable any of these features, at any time, to suit the needs of your network.  Your BuddyPress installation will continue to function and the disabled components will no longer be accessible to anyone using your site.

This is as simple as:

1.  Go to BuddyPress > Components

• Settings > BuddyPress > Components on a single WordPress install
• Settings > BuddyPress > Components in the network admin dashboard on a WordPress multisite install

2.  Select the components you want to disable and then click Save Settings.