An AddressBook is just a list of contacts in a Contacts folder that's
enabled as an address book, or it's a list of addresses from an Exchange
global address list (or from LDAP queries). You can only do what you want
for contacts.
Why not just go to the Contacts folder or folders, use Ctrl+A to select all
items there and click Delete or Shift+Delete to get rid of them all? It
would be a lot quicker than writing the code to do that for any Contacts
folders you have.
For importing you can just use the File menu's import rather than writing
code to import from a CSV file.
