All support docs are at https://support.wordpress.com/
Type in disconnect jetpack sites and click to search
Does this help?
Disconnect Jetpack Sites
We provide support only for wordpress.COM hosted sites. We do not provide support for
(1) local installs of wordpress.ORG software on your own server or
(2) wordpress.ORG software installs on paid hosting, and we do not provide support for them at wordpress.COM.
(3) Jetpack support https://jetpack.me/support/ for sites linked to wordpress.COM accounts with the Jetpack plugin so they display on the My Sites wordpress.com account page.
Some Jetpack solutions are here http://jetpack.me/support/
Others are in the Jetpack support forum at WordPress.org
However, if help cannot be found at either one then they can file a Jetpack support ticket here > http://en.support.wordpress.com/contact/?jetpack=needs-service
WordPress.COM and WordPress.ORG are completely separate and have different username accounts, logins, features, run different versions of some themes with the same names, and have separate support documentation and separate support forums. Read the differences here http://en.support.wordpress.com/com-vs-org/
As you are referring to a site that is not hosted here, and if you don't have a username account at WordPress.ORG account, then click http://wordpress.org/support/ and register one on the top right-hand corner of the page that opens, https://wordpress.org/support/register.php so you can post to the support forums there.
Resetting your WordPress.ORG password http://codex.wordpress.org/Resetting_Your_Password
WordPress.org support docs are at https://codex.wordpress.org/Main_Page
See also https://apps.wordpress.org/support/