On this page, you can see a list of all avatars in the system.
You can filter displayed avatars using the filter above the list. Possible filtering parameters are Avatar name, Avatar type (user or group avatar, avatars of type 'All' can be used for both) and Avatar kind (shared avatars are the pre-defined ones, while custom avatars are those that users uploaded from a file). Click Search to display only avatars matching the selected criteria.
You can Edit () or Delete () listed avatars.
More resources can be found at Developer's Guide -> Modules -> Avatars -> Overview.