It looks like exclude_admin only works if the admin’s login user name is admin.
exclude_admin
(boolean) Exclude the ‘admin’ (login is admin) account from the list. Valid values:
1 (true) – default
0 (false)
The strange part is that the Admin’s login is admin..
I will try if I am not connected with the admin user.
Well, you are missing a php in there. Try…
<?php wp_list_authors ('exclude_admin=1&hide_empty=0'); ?>