How to clear the Outlook Email Address Auto Complete Cache?

Outlook 2010:

1. Inside Outlook, type the email address you wish to clear from the cache until outlook displays it.
2. Select the email address and delete it with the delete button as shown below:
   
   

Outlook 2007:

1. Close your Outlook 2007 application.
2. Open Windows Explorer or IE and type %APPDATA%\Microsoft\Outlook into the address bar.
3. Delete the file Outlook.nk2 file in this folder if you are using the default profile name Outlook. If you have a different profile name (you can view it from Control Panel --> Mail --> Show Profiles... ), delete the file same as your profile name with the ".nk2" file extension.