Open Admin › Extension manager. Every bundled extension can be:
- Installed — creates its tables and adds its menu items.
- Disabled — hidden from the site, but its data is kept.
- Uninstalled — its tables and settings are removed.
Most extensions also have sub-features you can switch on or off, such as "no ads for members" in the Ad Manager or "click log" in Short URL. Extensions you receive as a zip can be uploaded from the same page.