To remove Saffire MixControl from your PC, you should first plug in your Saffire interface to uninstall the driver.
To do this, locate the Saffire in your device manager: Control Panel > System > Hardware > Device Manager
Vista: Control Panel > Hardware > Device Manager
Windows 7: Control Panel > Device Manager
Once you have found the Saffire under 'Sound, video and game controllers', you should right-click and choose 'Uninstall'. This is shown below:
Make sure to select the option to remove the driver from your computer
If you are asked to restart, please press 'No'.
After this, you should launch the 'Program and Features' utility (or Add/Remove Programs on Windows XP) in the Device Manager.
Once this is launched, you should locate Saffire MixControl, click on it, and select Uninstall from menu bar above. Once you have followed the on screen instructions and uninstalled Saffire Mix Control from your system, you should restart your computer.