The list of compters in the Screen Sharing application can become mighty cluttered. It’s common for the list to contain computers that don’t even exist anymore. You can remove computer names or IP addresses from this list.

The file that controls this list is located at /Users/yourusername/Library/Preferences/com.apple.ScreenSharing.plist. You can trash this file if you wish to clear the list out entirely. If you wish to just remove items from it, download and install the Property List Editor so that you can double-click this file to edit it.