I would suggest you to ask to Gideon either you can remove powered by or not.
Did none of these come up when you asked the question?
Try to edit qa-include/qa-theme-base.php and then find this line
'Powered by <A HREF="http://www.question2answer.org/">Question2Answer</A>',
Change it as you want. But i request to keep it if you are using free version. :)