The Workspace Switcher icon on Ubuntu Unity’s Launcher is a waste of space if you’re used to using keyboard shortcuts.
Workspace Switcher is un-customizable, it’s hard coded to unity and cannot be removed without hacking source code.

Option 1:

via imtx.me
Thanks to TualatriX, the developer of ubuntu-tweak who modified the code and added it into his personal PPA: https://launchpad.net/~tualatrix/+archive/personal

I’m not good at compiling codes and even not willing to spend time on it. So I tried this in Ubuntu 12.04 daily build. Installed (packages here):

libunity-core-4.0-4_4.24.0-0ubuntu2.1.1_amd64.deb
libunity-core-4.0-dev_4.24.0-0ubuntu2.1.1_amd64.deb
netbook-launcher_4.24.0-0ubuntu2.1.1_all.deb
unity-common_4.24.0-0ubuntu2.1.1_all.deb
unity-services_4.24.0-0ubuntu2.1.1_amd64.deb
unity_4.24.0-0ubuntu2.1.1_amd64.deb

Missing dependencies can be fixed by Synaptic.

Option 2:

If you’d like modifying the code and rebuild unity by yourself, follow the steps from askubuntu:

Make sure you have the package dpkg-dev installed

sudo apt-get install dpkg-dev

To modify the code and compile it your self you need to do the following

mkdir ~/code
cd ~/code
mkdir build
cd build
sudo apt-get source unity
cd unity*

Open plugins/unityshell/src/LauncherController.cpp with your favorite text editor, ie:

gksudo nano plugins/unityshell/src/LauncherController.cpp

Locate the lines

_num_workspaces = WindowManager::Default()->WorkspaceCount();
if (_num_workspaces > 1)
{
InsertExpoAction();
}

Change them to

/*_num_workspaces = WindowManager::Default()->WorkspaceCount();
if (_num_workspaces > 1)
{
InsertExpoAction();
}*/

Build the package

sudo apt-get build-dep unity
sudo debuild -us -uc

Wait for it to finish and install when done

cd ..
sudo dpkg -i unity*.deb libunity*.deb netbook*.deb