I dont think accounts can be closed, deactivated. The blockchain stores info permanently. I'm sorry this happened. Many new users feel the same. The problem is that Steemit is not like facebook or twitter where sharing content is encouraged. They DO NOT tell people that, rather wait until after and crudely pounce. You would think, they would want to notify and inform, politely and encourage the desired activity, guessing thats not what you got.
Isn't it odd an organization solicits new users from sharing platforms and then does this. Very odd.
You could just leave. I get that. Or you could tell this story. Now that would be original content. Nothing they can do about that. New users migrating from sharing platforms need to hear your story.