Here's the steps (my non-computer-savvy girlfriend had to figure this one out for me, but unlike all the far more complicated processes one can find online, this one works)

1. Open Control Panel
2. Click "Uninstall a Program"
3. Scroll down to Python and click uninstall for each version you don't want anymore.

This works on Windows 7 out of the box, no additional programs or scripts required.

Open Settings → Apps → Apps & Features.

.

Uninstall Python from there.

The python --version reply with the version of Python that is pointed to in your environment variables.

You should open the "System Properties" (you can use Windows key + Pause/Break to open it), go to the "Advanced" tab, and click on the "Environment Variables" button.

In the "System variables" section, look for the "Path" variable and select it, click "Edit" and search all the entries in the "Path" variable related to Python. These entries typically look like C:\Python{version}\ or %PYTHONPATH%.

Before removing them, go and delete the folder at the given paths; then remove the entries.

Finally, restart your pc.

Along with the things you've already done, this should completely remove Python from the system.

Solution:

UNHIDE ALL FOLDERS BEFORE FOLLOWING DOWN...

1. Go to C:\Users\%USERNAME%\AppData\Local\Programs
2. Delete Python Folder
3. Go to Control Panel >> Uninstall a Program
4. Right Click on Python and then Change/Modify
5. Click on Repair Python. Note: This may or may not fail, but be patient
6. Now Again go to step 3
7. Now, after step 3, uninstall Python

Now you should be able to install a new fresh version.