No form when logged in

I use Joomla 3 and would like to hide the form when a user is logged in. Can someone tell me how to manage this??

Thanks!

Hide which form? Registration form is redirected to user profile automatically when logged-in user tries to access it.

Yes, I have seen that. But in my opinion, it would be far more logical to remove the 'register menu-item' when logged in. Am I right that this isn't possible yet?

If you assign the access "Guest" instead of "Public" to your menu item it will disappear when you are logged in.