Since you are listed as "Former User" there is no account to delete in these forums. You former account has already gone.
So, which account do you wish to delete? If is your MAGIX Account, i.e. the account for your purchased Magix software, you will need to contact infoservice@magix.net and explain what it is you want to do. As far as I can see, there is no other method of doing what you want.