How do you remove it without removing the dependencies?
Code:
sudo dpkg -r --force-all libgl1-mesa-swx11
or (purge everything, I prefer this way)
Code:
sudo dpkg -P --force-all libgl1-mesa-swx11
WARNING:: Doing this will probably make your system unusable, DO NOT ATTEMPT UNLESS YOU UNDERSTAND THIS. Don't blame me if your system breaks.