How to Remove a Dock Icon in Mac OS X Lion
By default, the Dock in Mac OS X Lion comes stocked with icons that Apple thinks you’ll need most frequently, but you can customize it to contain any icons that you choose. Removing an item from the Dock in Mac OS X Lion is an easy two step process. Just drag an icon out of the Dock, and it disappears with a cool poof animation.
Choosing Remove from Dock from the item’s Dock menu is another way to make the item go away.
You can’t remove the icon of a program that’s running from the Dock until you quit that program. Also, note that by moving an icon out of the Dock, you aren’t moving, deleting, or copying the item itself; you’re just removing its icon from the Dock. The item is unchanged. The icon is sort of like a library catalog card: Just because you remove the card from the card catalog doesn’t mean that the book is gone from the library.
Although you can add several items to either side of the divider line at the same time by selecting them all and dragging the group to that side of the Dock, you can delete only one icon at a time from the Dock.
Put things in the Dock that you need quick access to and that you use often, or add items that aren’t quickly available from menus or the Sidebar. If you like using the Dock better than the Finder window Sidebar (for example), add your Documents, Movies, Pictures, Music, or even your Home folder or hard drive to the Dock.