In case you have removed your old SohoLaunch but you encounter this error message when trying to make a fresh SohoLaunch installation through cPanel -> Fantastico, you should remove the following files, located in your account's home folder > .fantasticodata:

Soholaunch_Pro_Edition_installed.php
soholaunch.cache

Once you have deleted the above-mentioned files, you should be able to install your SohoLaunch Pro Edition normally.