Having tested this using Python 3.5 and pip 7.1.2 on Linux, the situation appears to be this:
pip install --user somepackageinstalls to$HOME/.local, and uninstalling it does work usingpip uninstall somepackage.- This is true whether or not
somepackageis also installed system-wide at the same time. - If the package is installed at both places, only the local one will be uninstalled. To uninstall the package system-wide using
pip, first uninstall it locally, then run the same uninstall command again, withrootprivileges. - In addition to the predefined user install directory,
pip install --target somedir somepackagewill install the package intosomedir. There is no way to uninstall a package from such a place usingpip. (But there is a somewhat old unmerged pull request on Github that implementspip uninstall --target.) - Since the only places
pipwill ever uninstall from are system-wide and predefined user-local, you need to runpip uninstallas the respective user to uninstall from a given user’s local install directory.