How to fully uninstall Python from Windows?

[snippsat]

What is the procedure to remove Python entirely from Windows, so I can reinstall and be done with it?

You just use the Windows Uninstaller.
Then look at Python 3.8 (3.6-3.7) and pip installation under Windows.

For fixing error you have this may work.

python -m pip install --upgrade --force-reinstall pip

But if want a new install follow link,and no need to use pip3.
Test with Python -V and pip -V after install,shall work from anywhere in cmd.