Redmine

Hi everybody,
I have read the feature #2585 and also I have tried to do that :
To Hide Activity Tab, remove the following line from redmine\lib\redmine.rb
menu.push :help, Redmine::Info.help_url, :last => true
But nothing works, the activity tab is still there. I´m working with redmine 1.3, someone has a clue about what do I have to do?
I will appreciate some help :)
Thanks