There is no easy way to select all contacts and delete them using the standard Blackberry handsets Contacts application. Here is a way of doing so using a little Blackberry-Fu:

  1. Go to Contacts application.
  2. Press the menu button.
  3. Select Options.
  4. On the Options screen type rset.
  5. You will be prompted “This will erase your Desktop contact list, and reload it from your server. Continue?” (where Desktop is the name of the selected Contacts list).
  6. Select Yes.
  7. If you have multiple Contact Lists then it will cycle through them all offering the option to delete them.

If the Contact List is set to sync with your BES then it should then sync down all of your contacts again. This is useful if you activate a Blackberry which is already connected, to a BES, and it creates duplicate contact lists.