Delete File in MEDIA when is not used in a Layout

Hello,
In the version 1.7 in the media screen we have a option to find a orphan file to delete that in the version 1.8 where is this option?

Tidy Library routine will remove files that are currently not assigned to any layout / display.

It should be accessible from Library page and CMS Settings page, if it’s not please see CMS Settings -> General tab -> Enable Library Tidy?