First of all, we would be sad to see you leave. We would be happy for any feedback as to why, so we can improve our service in order to re-gain you as a user again in the near future.
To discuss what we can do to get you to stay with us, please either submit a support ticket or contact live support and we will be happy to speak to you.
If you are 100% certain you'd like to close your account, you can of course do this here under 'Account options'.