How to remove user session attribute saved in namespace 'foo'?

To remove a user session attribute foobar' saved in the default name space, simply do this:

$user->getAttributeHolder()->remove('foobar');

How do you remove attribute foobar if it was saved in namespace foobar like t开发者_开发技巧his:

$user->setAttribute('foobar', 123, 'foo');

I think you can specify the namespace like this :

$user->getAttributeHolder()->remove('foobar','','foo');