A quick guide on how to remove the bubble background from unity launcher. However there is no official way but there is a workaround available to replace the original files with the edited. Root access is required.
1)>> Download Edited Files
2)>> Create backup folder and copy original files in it:
cp /usr/share/unity/icons/* ~/Documents/backup
3)>> Now extract the downloaded files in /usr/share/unity:
sudo tar zxvf ~/Downloads/edited-icons.tar.gz
Now Logout or Restart your system, the icons background will be removed by now.
Now to get the old tiles back just copy the backup icon again to replace the edited one.
sudo cp ~/Documents/backup/* /usr/share/unity
Done!! Restart again for changes to take effect.