Problem:

You have an issue with a Python version (e.g. the 3.7 version) and want to install another version (e.g. the 3.6 version). In order to install a fresh version you need to uninstall the current version first.

Solution:

Assume that the current version is 3.7. Replace 3.7 with another version that you installed.

Follow these 3 steps below.

1. Remove the third-party Python 3.7 framework

sudo rm -rf /Library/Frameworks/Python.framework/Versions/3.7

2. Remove the Python 3.7 applications directory

sudo rm -rf "/Applications/Python 3.7"

3. Remove the symbolic links, in /usr/local/bin, that point to this Python version. Ensure that the links exit using below command

ls -l /usr/local/bin | grep '../Library/Frameworks/Python.framework/Versions/3.7'

then run the following commands to remove all the links:

cd /usr/local/bin/
ls -l /usr/local/bin | grep '../Library/Frameworks/Python.framework/Versions/3.7' | awk '{print $9}' | tr -d @ | xargs rm

Installing a new version:

1. Download a version from https://www.python.org/downloads/mac-osx/, double click the file and follow the instructions.
2. Verify installation: python3 –version
3. Install Homebrew from https://brew.sh
4. Install virtualenv

pip3 install virtualenv
pip3 install virtualenvwrapper

5.  Create and activate a virtual environment

cd /Users/admin/Downloads/training_model/model 
python3 -m virtualenv /Users/admin/Downloads/training_model/model
source bin/activate