The simplest way is to drag and drop the game from the Application's folder to the Trash, then right click the Trash icon and choose Empty trash.
If this method doesn't work, then go to Spotlight and type Terminal. Issue the following command mdfind -name "application name" replacing "application name" with Amanda.
After is displays the path to the installation, type rm -rif PATH. Simply copy the PATH from the lines above the command.
Eventually reboot your Mac to complete the uninstall process.