If you decide you don't want to use E-goi anymore (sniff, please tell us why!), you can simply stop using it. The account will be automatically deleted after some time.
But if you'd rather delete it right now, just follow these steps:
1) Log into your E-goi account and go to your user menu (upper right corner).
2) Select "Account settings". A new page will come up. Hit the "Delete this E-goi account" button and fill in the confirmation form.
Done! Your account will then be deleted in a couple of days.