See if that helps you...
Step 1 - The panel.
Go to the Wordpress panel in your account. Look for the menu on the left, where it says "Settings".
Go to "Blog Address (URL)" where you can determine how we want to open the blog, which will be the main address to be used to access your pages. Above you always use the directory address to access your account, but below you can choose the main domain.
So, where is "Blog address (URL)" leave only the main address. Scroll down the page and save the changes.
Step 2 - Modifying the Index.PHP file
It will get a little more complicated now. In the "wordpress" folder you installed in your hosting service, there is a file called "INDEX.PHP. You may even have it backed up on your PC. Save it and open it in Notepad to see the source code.
Has a line there that looks like this : require('./wp-blog-header.php');
Replace it with : require('./wordpress/wp-blog-header.php');
Save with the same name by overwriting the old file. Go back to the hosting directory and upload this file outside the "wordpress" folder, in the main public folder of your domain.
Done. Now your blog already has the address redirected to the main URL, outside the directory.
source: br.forums.wordpress.org