If you're trying to remove a video source from the SlingStudio Console app, but find that you can't do it, check to make sure that the video source is not in use by appearing in the Program window (the window that shows the video source currently being used for your project).
A video source cannot be removed if that source appears in the SlingStudio Console app Program window.
Try choosing another video source and promoting it to the Program window. You should then be able to remove the other video source.
By the way: Want to rearrange the order of your video source thumbnail images? Just tap and drag (SlingStudio Console for iPad) or click and drag (SlingStudio Console for Mac) the video source thumbnails into the order that you'd like.