This set of tools, which work only for members of the "admin" group, include two features, Force Mute and Disconnect, that are accessed by right-clcking on another person's avatar:

 

and one feature, Turn Invisible, that is accessed by right-clicking on your own avatar:

When an administrator selects "Force Mute," the person being muted receives a message explaining what has happened:

That user may unmute themselves at any time.

Extreme care should be taken before choosing to disconnect a user. If an administrator selects this command, the user will immediately be disconnected from the session and will receive a message:

The Turn Invisible command allows an administrator to walk around the world unseen by anyone not in the admin group. The administrator, plus other admins, will see an invisible avatar surrounded by animated spheres.

Right-clicking on your awn avatar again will allow you to select "Turn Visible" to turn your avatar back on for others.

Version 0.2 adds a web UI that allows administrators to view connected users, as well as mute and disconnect users from the web admin page: