code: public void destroy(GSSCredential credential,
                          String username,
                          String passphrase)
          throws MyProxyException {
          DestroyParams request = new DestroyParams();
          request.setUserName(username);
          request.setPassphrase(passphrase);
          destroy(credential, request);
      }
docs: Removes delegated credentials from the MyProxy server.
  
  @param  credential
  The local GSI credentials to use for authentication.
  @param  username
  The username of the credentials to remove.
  @param  passphrase
  The passphrase of the credentials to remove.
  @exception MyProxyException
  If an error occurred during the operation.