A Blog by DotJoomla
Here we can see How to hide a menu item, module, content from a logged in user in Joomla 1.6+
Step 1. Go to user manager, create a new user group 'Guest'. Make it a child of Public group.
Step 2: Create a new access level 'Guest' and grant only the Guest group access to this level.
Step 3: Go to user manager -> Options -> component and change the Guest User Group from from the default value of "Public" to "Guest".
Step 4: Now simply assign a menu item, module or content to the Guest access level. This can only be seen by non-logged in users.