python 3 and python 2 pips not working in windows

[snippsat]

That's link is not the ideal way of doing this.
Just use py to access all other version installed.
Then there is no need to mess with or rename python.exe.
Explain all in here also usage of py Python 3.6/3.7 and pip installation under Windows

python and pip use the main most used version.

E:\div_code
λ python -V
Python 3.7.3

E:\div_code
λ pip -V
pip 19.2.1 from c:\python37\lib\site-packages\pip (python 3.7) 

Use other version.

E:\div_code
λ py -2.7 -V
Python 2.7.9

E:\div_code
λ py -3.4 -V
Python 3.4.2

E:\div_code
λ py -3.5 -V
Python 3.5.2

# Install to 2.7
E:\div_code
λ py -2.7 -m pip install requests
Requirement already satisfied: requests in c:\python27\lib\site-packages (2.18.4)