If you are bothered by our survey invitations you can simply disable the email notifications from your profile settings page. This way you can still login and check for new surveys whenever it’s convenient to you.
Otherwise you can end your membership with myiyo anytime you like and delete your account by submitting a form online. You can find the "delete account" button in your profile settings (in the top-right corner). You have to be logged in first in order to access the deletion form.