remove all references to python 3.7 on ubuntu code example

Example: remove all references to python 3.7 on ubuntu

# The following commands will remove your make altinstall-ed python:

rm -f /usr/local/bin/python2.7
rm -f /usr/local/bin/pip2.7
rm -f /usr/local/bin/pydoc
rm -rf /usr/local/bin/include/python2.7
rm -f /usr/local/lib/libpython2.7.a
rm -rf /usr/local/lib/python2.7
# You might also have to do

rm -f /usr/local/share/man/python2.7.1
rm -rf /usr/local/lib/pkgconfig
rm -f /usr/local/bin/idle
rm -f /usr/local/bin/easy_install-2.7