I reported this as abuse so a mod will see and respond to your request but
with it being a holiday weekend you may not get an answer till Monday.
Are you wanting to delete your Support Community account or My T-Mobile account? If you're referring to your Support Community account, that's something I can help out with. If your My T-Mobile account, the only option available would be to deactivate your login and that can only be done by contacting us.
(I'll reply as fast as possible but all of the Community Managers are off until Monday. I'm on-call! )