If you need to uninstall, or reinstall, the Focusrite RedNet thunderbolt driver, please follow the instructions below:

• Open the Finder window and navigate to: Mac HD > Library > Extensions
• Move the FocusritePCIe.kext file to your trash bin 
  • If you are using a RedNet PCIe card, remove the FocusriteRedNetPCIe.kext file
• Empty your trash
• Restart your computer

If you need to reinstall the driver for a Red interface (Red 4Pre, Red 8Pre, Red 8Line, Red 16Line), then you can find the latest download for your interface here: Focusrite Pro Red Downloads

Please note that the latest driver for RedNet PCIe cards will be included when installing the RedNet Control software. You can find the instructions to reinstall RedNet Control here: How to fully uninstall RedNet Control 2 from your Mac