How can I delete a class from my project?

It's not as easy as it seems. Unfortunately, the Class Viewer doesn't directly support this option, so you have to a lot of work. First, you have to start by removing the .h and .cpp files that implement the class itself. You do this by switching to the 'File' pane of the Class Viewer (that thingy with the three panels: Classes, Resources and Files), selecting the files and pressing the Delete Key in your keyboard. Be aware, however, that this won't delete the actual files, you still have to do it manually from explorer.

Now, you have to go through your code searching for places where you've used the class, and remove those occurrences. You'll also need to delete any #include statements that involve the class .h file.