Move an app to applications when it's installed itself elsewhere
tl;dr: drag SmartGit.app to your applications folder (or wherever you want to install it) and eject (remove) the img (drag this SmartGit 18.1.2 folder to trash bin)

You didn't install it yet, you only opened a disk image (hint, the format of the file you downloaded is probably .dmg) which contains the app itself (the .app file). You can now drag this app to your applications folder or wherever you want it. Usually these installers contain these steps, and a shortcut to default applications folder, so you just drag a few steps. But it's the exact same thing.