Erase Your Mistakes In Two Clicks
So you filled up the Stage with what now seems like a tragic error in judgment. The layout is all wrong, the custom scrollbar is the worst you've ever made, and the text may as well have been written by a five-year old. It's time to clean up.
To erase everything on the Stage, double-click the Eraser tool in the toolbar. Problem solved. Note, however, that this works only one frame at a time. When the playhead is at frame 10, you can erase everything on the Stage at frame 10, but nothing else. To erase other frames, you have to move the playhead to those frames.