Manual:$wgImplicitGroups

User rights, access control and monitoring: $wgImplicitGroups
Groups that aren't shown on Special:Listusers or somewhere else
Introduced in version:1.12.0 (r28797)
Removed in version:still in use
Allowed values:(Array of group names.)
Default value:[ '*', 'user', 'autoconfirmed' ] (1.13+)
array( '*', 'user', 'autoconfirmed', 'emailconfirmed' ); (1.12)

Details edit

$wgImplicitGroups is an array of groups that are not shown in Special:Listusers and on a few other places. Note that they cannot be assigned through Special:Userrights.

Syntax example edit

// defining a set of user groups which should not be shown
$wgImplicitGroups = [ '*', 'user', 'autoconfirmed', 'emailconfirmed', 'sysop', 'bureaucrat', 'bot' ];
// adding a single user group to an existing set
$wgImplicitGroups[] = 'bot';

Note edit

It would hide only group names in the menu, not the users themselves.

See also edit