In your cPanel File Manager or FTP, are the forum files still there in public_html?
If so, please go into public_html and delete/rename the file named index.html.
That site is linked to a different forum name as well; how long has it been since you last saw that site active? Cause if it was suspended for inactivity (failure to login to the forums once every 31 days as the TOS requires) and then terminated, the domain pops up for anyone to register under, and it appears that may very well be the case here.
btw, you should use [nuked - this should not have been posted due to data protection] forum account to make any request for http://rebel.x10.mx and to keep it active you need to login here with that username at least once a month.
Then yeah your old account would've been erased along with all content; the user mentioned above is the new owner on that domain. Sadly it's a common-enough domain name choice that once it was marked as unused someone probably snagged it almost immediately.
You're still able to sign up for a new account, but since that domain is now in use, you'd have to use a different one.