Please Note: 404 page is a default page of WordPress. So, there is no option to deactivate the page form any theme.
However, you can try deleting the 404.php template in the theme folder. I’m not sure how WordPress will handle that though. It may just load the index/home instead if there is no 404 template.
I found this which may help, http://wordpress.stackexchange.com/questions/24587/
Best Regards,
ThemeLooks Support Team