A. Firstly you have to stop domain x trusting domain y, then remove domain x's ability to trust domain y:

  1. Logon as Administrator to domain x
  2. Start User Manager for Domains, and click Trust Relationships from the Policies menu
  3. Select domain y from the Trusted Domains and click Remove and confirm
  4. Logoff, and logon to domain y as Administrator
  5. Start User Manager for Domains, and click Trust Relationships from the Policies menu
  6. Select domain x from the Trusting Domains and click Remove and confirm
  7. Exit