From their FAQ (http://site4.way2sms.com/content/privacypolicy.html)
To have your account removed, send an email to firstname.lastname@example.org. You’ll receive a 4 digit unique number on your registered mobile phone. You can use this to delete your account.
It’s not entirely clear for us where this 4 digit number can be used because we do not have access to an Indian mobile phone. Perhaps you can help us out? Leave us a comment!