The correct place for support is here. There is no telephone service or email address.
If you want help you'll need to give more details. What do you mean by "cancel my account"?
If you are forum owner and wish to close it, go to:
Options > Delete
If you are a registered user of a forum hosted by Nabble then login in to that forum, then click on your username towards the top right and follow the options:
Account settings > Remove your account
If you want to do something else, please explain what you have in mind.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.