And you can activate/deactivate it for all users via:
To get around this log in via putty then:-
1. Type “tt” at command prompt and hit enter, screen will echo back:-
psql (9.3.

Type "help" for help.
2. Type the following at command prompt:-
update intl_enterprise_user_settings set group_presence_control_flag=1/0;
System will reply with “UPDATE <<user number>>
3. Type \q to quit.