How to disable Spotify indicator in the top panel?

For Spotify version 0.8.8 and earlier

The best way to do this is to remove the icon used by spotify to display the indicator. This can be done by executing the following command in the terminal,

sudo mv /usr/share/spotify/theme/other/_linux/icon.ico /home/user_name/icon.ico

Replace user_name with your user name. This should effectively disable the spotify indicator. Exit spotify and restart spotify to notice the change.

For versions higher than 0.8.8

open up a terminal and open the zip file as root:

gksu file-roller /opt/spotify/spotify-client/Data/resources.zip

Then, inside the zip file, navigate to the _linux subfolder and delete the .ico files inside it. That's it.

It could be worth trying to use apparmor to prevent spotify from loading the icon.

/etc/apparmor.d/usr.bin.spotify

/usr/bin/spotify {

  # deny read access to the icon
  deny /usr/share/spotify/theme/other/_linux/icon.ico r,
}

sudo /etc/init.d/apparmor reload

Wait for a few seconds and try running spotify again.

For more recent versions of Spotify the solution proposed by Nik no longer works. This is because the config files have been put inside a zip file, which is located at /opt/spotify/spotify-client/Data/resources.zip.

You could do essentially the same as Nik proposed. First, open up a terminal and open the zip file as root:

gksu file-roller /opt/spotify/spotify-client/Data/resources.zip

Then, inside the zip file, navigate to the _linux subfolder and delete the .ico files inside it. That's it.