Delete local changes in Xcode?

I imported an external project into my project by dragging its project file into mine. It didn't work. Now those files show up whenever I check something in. I don't want them and I never select them at checkin, but how do I get rid of them? I don't find them in the underlying file system, and I haven't found any controls that will get rid of them. They appear in the source control navigator under the changes tab as Local Changes.