Changing website URL?

[Fulla]

How do you change the URL of your main forums? I followed a few tutorials, but couldn't get it working.

For some reason my forums add a second 'forums/' in to the url link. I simply want to remove this.

My main website is www.sc2arcade.com
My forums have become www.sc2arcade.com/forums/forum.php

I just want www.sc2arcade.com/forum.php

Please help?