[polyorchid]

If you are just clearing selected the bits you are throwing away are still in your hard drive. You could delete, but you still have to hold down the enter or return button. shift-control-u, shift-control-b is the key command to get there.

The other way to clear everything that is'nt being used in your session with out the thousands of "are you sure...?", is to select all of your used regions in your edit window then "compact selected." This will clear everything that is'nt being used in your session, so do this at key times in your session like the very end or before laying key parts then backing up.