You have full control over access in the HWDMediaShare gallery and can restrict access in numerous ways. This documentation aims to give an overview of the main restriction options.
Offline mode
You can quickly put the HWDMediaShare gallery offline in the HWDMediaShare configuration Site tab. This will prevent access to all Joomla users.
You can also set an Offline redirect (see below) Joomla article to which all users will be directed when the gallery is offline. This is useful for explaining why the gallery isn't available.