MacOS – Unable to upgrade to python 3.6 from python 2.7

I'm trying to remove python 2.7 and replace it with python 3.6. The main thing I want to do is type "python" and my terminal use python 3.6, but for some reason I'm being restricted from upgrading python.

I installed python 3 with:

brew install python3

Below are the commands I'm running. Would some one please help me out?

Guys-MacBook-Pro:bin guy$ python --version
Python 2.7.10

Guys-MacBook-Pro:bin guy$ python3 --version
Python 3.6.5

Guys-MacBook-Pro:bin guy$ whereis python
/usr/bin/python

Guys-MacBook-Pro:bin guy$ whereis python3

Guys-MacBook-Pro:bin guy$ pwd
/usr/bin

Guys-MacBook-Pro:bin guy$ ls -l | grep python
-rwxr-xr-x   1 root   wheel     66880 Mar 27 23:03 python
-rwxr-xr-x   4 root   wheel       925 Oct  7  2017 python-config
lrwxr-xr-x   1 root   wheel        75 Apr  2 15:56 python2.7 -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7
lrwxr-xr-x   1 root   wheel        82 Apr  2 15:56 python2.7-config -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7-config
-rwxr-xr-x   1 root   wheel     66880 Mar 27 23:03 pythonw
lrwxr-xr-x   1 root   wheel        76 Apr  2 15:56 pythonw2.7 -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/pythonw2.7

Guys-MacBook-Pro:bin guy$ ls -l /usr/local/bin|grep python
lrwxr-xr-x  1 guy  admin  43 Apr 16 15:25 easy_install-3.6 -> ../Cellar/python/3.6.5/bin/easy_install-3.6
lrwxr-xr-x  1 guy  admin  31 Apr 16 15:25 pip3 -> ../Cellar/python/3.6.5/bin/pip3
lrwxr-xr-x  1 guy  admin  33 Apr 16 15:25 pip3.6 -> ../Cellar/python/3.6.5/bin/pip3.6
lrwxr-xr-x  1 root           wheel  69 Apr 16 12:42 python3 -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3
lrwxr-xr-x  1 root           wheel  76 Apr 16 12:42 python3-config -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3-config
lrwxr-xr-x  1 root           wheel  71 Apr 16 12:42 python3.6 -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6
lrwxr-xr-x  1 root           wheel  78 Apr 16 12:42 python3.6-config -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6-config
lrwxr-xr-x  1 root           wheel  72 Apr 16 12:42 python3.6m -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6m
lrwxr-xr-x  1 root           wheel  79 Apr 16 12:42 python3.6m-config -> ../../../Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6m-config
lrwxr-xr-x  1 guy  admin  33 Apr 16 15:25 wheel3 -> ../Cellar/python/3.6.5/bin/wheel3


Guys-MacBook-Pro:bin guy$ sudo ln -s /Library/Frameworks/Python.framework/Versions/3.6/bin/python3 python
ln: python: Operation not permitted

Guys-MacBook-Pro:bin guy$ sudo su

sh-3.2# pwd
/usr/bin

sh-3.2# ln -s /Library/Frameworks/Python.framework/Versions/3.6/bin/python3 python
ln: python: Operation not permitted

sh-3.2# exit
exit

Guys-MacBook-Pro:bin guy$ sudo su -

Guys-MacBook-Pro:~ root# cd /usr/bin

Guys-MacBook-Pro:bin root# ln -s /Library/Frameworks/Python.framework/Versions/3.6/bin/python3 python
ln: python: Operation not permitted

Guys-MacBook-Pro:bin root#