Please open a SSH shell. You do not need to use a root shell to install ws2812. If a normal unprivilidged user exists you should start the installation with this user.
sudo apt-get update
sudo apt-get install gcc make build-essential python-dev git scons swig
sudo echo "blacklist snd_bcm2835" > /etc/modprobe.d/snd-blacklist.conf
git clone https://github.com/jgarff/rpi_ws281x
cd rpi_ws281x/
sudo scons
cd python
sudo python3 setup.py build
sudo python3 setup.py install
sudo pip3 install adafruit-circuitpython-neopixel
sudo reboot
Or use the automatic installer
curl -sL http://titomoskito.com/ws2812/install.sh | sudo bash -
Set the Data Line to GPIO18
That's it :)
Tested with Raspberry Pi Zero WH