Need to delete my domain registed before to recreate new one

Need to delete my domain registed before to recreate new one

I've created a domain name kinhdotelecom.com.
But now I can't add user, delete or can't do anything with it.

I've closed my account, but my domain still remain on your system and can't create new one (kinhdotelecom.com)

Pls help me to fully delete it from your system, I'll create new

Regards!