I've installed opencv from source using a virtualenv, however I faced some errors and needed to reinstall it. I tried removing all the files with `sudo find / -name "opencv" -exec rm {} \;` and checked if the package was removed with `pkg-config --modversion opencv`, and it said it could not be found, but when I open the terminal with `python3` and enter `import cv2` then `print(cv2.__version__)`, the terminal returns `4.0.0`. How can I completely remove opencv? I'm on Ubuntu 18.04 LTS.