Thank Joe/ Ira.

I go to DU, and select the disk I want to unify.
There is + but not a minus.

I click on the small pie one nothing happens.

I even changed 75gb to 0 gb was apply still greyed out. Here is image. Don't mind erasing everything.
[IMG]http://i67.tinypic.com/dlnyc2.png[/IMG]