Delete Microsoft account or change password

1. Now that I have Telstra mail, how do I delete redundant Microsoft accounts? When I try, I get the message, "The account you're trying to close is part of a managed domain. You need to contact the domain's administrator to close this Microsoft account."

2. In the instructions for converting to Telstra Mail, it suggests changing your MS account password once Telstra Mail is working. When I try this, I get the message, "You can't complete that task here. To continue, you need to go to your organization's web site."

How do I do these these two things, any ideas?