Hmm, strange. Is there no unmount/eject option when you right click on the drive icon ?
Also, if you want to find where a .app file (application) is located, you can do so by simply right clicking its dock icon (if it's not always in the dock, run the app first), and choosing Options > Show in Finder. Then, after you've quit the running app, simply delete that .app file from Finder.
Sometimes, in my experience, apps will provide an uninstall script (usually either a shell script or Applescript), often located within the Contents folder when you open up the app file in Finder (right-click on .app file > Show Package Contents), that may need to be run by you, prior to deleting the .app file, to completely rid your system of the app and all its configurations/files, but in most cases, apps can be uninstalled simply by deleting the one .app file.