How to to remove USB stack from Feather M0

Board: Adafruit Feather M0 Adalogger
Editor: VS Code with PlatformIO
Debugger: J-Link EDU
Framework: Arduino

I want to remove all trace of the USB stack from my code to free up space in Flash for my own code. I don’t need a serial port for upload or debug as I am using a J-Link. I have overwritten the built-in bootloader.
I have tried using build_unflags =-DUSBCON -DUSE_TINYUSB in platformio.ini and all sorts of other combinations but without sucess. Any ideas how to remove the USB stack?