Many times you install Joomla in a sub-directory and then want to move it to a higher level directory, here's a short tutorial on how to do it. Note that this is written for Joomla 1.5, in case you are still using Joomla 1.0, migrate now!
Say you have installed Joomla in the following folder public_html/tryjoomla Now that you are satisfied with the site, you'll want to move to public_html
1. Move all the files from the sub-directory to the upper level directory, you can use your favourite FTP client or the panel that your hosting service provides to do this.
2. Download and open the configuration.php file in a text editor.
3. Look for the following variables
var $log_path var $tmp_path var $ftp_root var $live_site
The first two will definitely have a long value, the other two might not. The first line will most probably look something similar to
var $log_path = '/home/username/public_html/tryjoomla/logs';
You need to change this to
var $log_path = '/home/username/public_html/logs';
We've simply removed the tryjoomla folder name from the path. Similarly change the tmp path
var $tmp_path = '/home/username/public_html/tmp';
If you have the $live_site and $ftp_root variables with some values, they too need to give up the tryjoomla folder, so they can look something like
var $live_site = 'http://www.yoursite.com/tryjoomla';
var $live_site = 'http://www.yoursite.com';
var $ftp_root = 'public_html/tryjoomla';
var $ftp_root = 'public_html';
If you have cache enabled, you will need to login to the administrator (Which will now be at http://www.yoursite.com/administrator and not http://www.yoursite.com/tryjoomla/administrator), and go to Tools -> Clean Cache and delete all cache files.