VCP driver for my Macintosh; late 2015 Where do I find my "AppleUSBFTDI.kext" in my system?

I am trying to load a different a FTDI VPC driver to use with my Lenz USB 23151 for use with my Macintosh (a late 2015 iMac 21.5" with a 10.13 Beta).

I am told to remove it in order to load a FTDIUSBSerialDriver_v2_4_2.dmg
The kernel extension AppleUSBFTDI.kext is located at /System/Library/Extensions/. The kext is protected by System Integrity Protection, which has to be disabled if you really want to remove it. 

Disabling SIP is addressed in this answer.