Linux, Hosting tips

How can I move all the files from that folder to the main directory without damaging or changing anything?

Moving the Joomla files and folders up one level will not damage them. You will need to edit your configuration.php file in a text editor to remove the joomla folder from the path for your tmp and log folders. You may also need to rename the welcome.html file to welcome.old or just remove it from your root folder.

If you are using Jooma 1.5.x no configuration file changes should be necessary. You can simply move the files to the new location.

If you are using 1.0.x then you will need to edit the configuration.php file.