Once you have applied for a Host account, you cannot change it back to a Guest account.
Even if your account is registered as a host, you can still access features as a guest as well, so keeping the Host account should not be a problem. If you want to stop emails and notifications intended for hosts, you can do so by changing the settings under the Notification settings.
If you wish to re-register as a Guest, cancel your existing account first and then register a new account.