Please remove the following:

Macintosh HD/Applications/Saffire MixControl.app

Macintosh HD/System/Library/Extensions/Saffire.kext (if present)

Macintosh HD/Library/Extensions/Saffire.kext

Macintosh HD/Library/Startup Items/Saffire/.*

Macintosh HD/Library/Application Support/Saffire/.*

Macintosh HD/Library/Audio/MIDI Drivers/SaffireMIDIDriver.plugin

Macintosh HD/Users/[yourusername]/Library/Application Support/Focusrite/.*

Macintosh HD/Library/Receipts/Install Saffire MixControl.pkg

* indicates that you should delete the entire folder. This folder is located in the User Library, to locate User Library: Go to the Finder (or desktop)>Hold the Option key on your keyboard, and click the Go menu at the top of the screen>With the Go menu open, you'll notice that pressing and releasing Option will display or hide the Library choice in this menu. 

Finally, go to Finder > click 'Go' at the top of the screen > Go to folder > type /var/db/receipts > remove the following files:

com.focusrite.SaffireInstall.pkg.bom

com.focusrite.SaffireInstall.pkg.plist

tc.tctechnologies.pkg.Saffire.audio_driver.bom

tc.tctechnologies.pkg.Saffire.audio_driver.plist

tc.tctechnologies.pkg.Saffire.midi_driver.bom

tc.tctechnologies.pkg.Saffire.midi_driver.plist