The easiest way to remove your Gallery installation is to first delete all databases and database users associated with your Gallery installation. Then, use your favorite FTP client to remove all installation files.
You may find when trying to remove a Gallery 3 installation from your web server that the /var directory just don’t delete. For some reason, Gallery sets that directory with weird permissions so you must be logged in as a root user to remove it. If you cannot SSH or have local access, ask your web host to delete /var for you using sudo or root access.
On a basic LAMP server running CentOS 5.x, you may find your Gallery installation at /home/username/public_html/gallery directory/var
Once you are in /gallery directory/, which is where your Gallery is installed, run the UNIX command “rm -r var” and all your files that FTP or your web server’s control panel couldn’t remove will now be deleted.
Please note this removal guide applies only to Gallery 3 beta and release candidate installations. The final version has not been released yet.