How to Get Rid of Icons in Mac OS X Lion
Trashing an alias gets rid of only the alias, not the parent file. But trashing a document, folder, or application icon puts it in the Trash, where it will be deleted permanently the next time you empty the Trash. The Finder menu offers a couple of commands that help you manage the Trash:
Finder→Empty Trash: This command deletes all items in the Trash from your hard drive.
Use this command with caution. After a file is dragged into the Trash and the Trash is emptied, the file is gone, gone, gone unless you have a Time Machine or other backup.
Finder→Secure Empty Trash: Choosing this command makes the chance of recovery by even the most ardent hacker or expensive disk-recovery tool difficult to virtually impossible. Now the portion of the disk that held the files you’re deleting will be overwritten with randomly generated gibberish.
If you put something in the Trash by accident, you can almost always return it whence it came: Just use the Undo command. Choose Edit→Undo or press Command+Z. The accidentally trashed file returns to its original location.
Unfortunately, Undo doesn’t work every time, and it remembers only the very last action that you performed. So don’t rely on it too much.