If you like the email notification aspect of the Indicator Applet, but want to get rid of the volume button that by default rests to the left of it – especially if you plan to restore the original Ubuntu volume button – don’t worry, as it’s quite easy.
The package indicator-sound is all that needs to be removed, which you can do by pasting the following into a terminal:
sudo apt-get purge indicator-sound
Then just restart the panel with:
When the panel reloads, the volume indicator will be gone.