This is because every @hotmail.com and @msn.com e-mail address is automatically a .NET Passport, so you cannot delete your .NET Passport without also closing your MSN Hotmail or MSN e-mail account.
Ker sta vsak @hotmail.com in @msn.com e-poštni naslov samodejno tudi .NET Passport, ne morete izbrisati .NET Passporta, ne da bi hkrati zaprli tudi MSN Hotmail ali MSN e-poštni račun.