User based projects

For the team functions, it should be possible to have user based projects. If I have three members but the third member is not supposed to know about a certain project I now can't remove that third member from seeing the project. This should be a really fast quickfix. There is already a button under the project -> share project -> member -> remove. But this button doesn't do antyhing. Also the leave button in the project also doesn't do anything at all.