The installation procedure installs everything into a single directory, and creates a symlink to the executable in /usr/local/bin. You can use the command pyformex -whereami to find out where pyFormex is installed.
Finally, a pyFormex installation can usually be removed by giving the command pyformex -remove and answering 'yes' to the question. You may want to do this before installing a new version, especially if you install a new release of an already existing version.