Before asking this question, I tried a lot of methods. I mainly focus on these posts.
How to find all python installations on mac os x and uninstall all but the native OS X installation
How to clean iPython environment so I can start over with Jupyter and Python 3.x?
I also tried
conda install anaconda-clean
anaconda-clean --yes
rm -rf ~/anaconda3
brew cleanup python3
But I still have a number of python versions left
GZs-MacBook-Pro:bin gz$ which python
/usr/bin/python
GZs-MacBook-Pro:bin gz$ which python3
/usr/bin/python3
GZs-MacBook-Pro:bin gz$ ls /System/Library/Frameworks/Python.framework/Versions
2.3 2.5 2.6 2.7 Current
GZs-MacBook-Pro:bin gz$ ls /Library/Frameworks/Python.framework/Versions
ls: /Library/Frameworks/Python.framework/Versions: No such file or directory
GZs-MacBook-Pro:bin gz$ ls -l /usr/bin/python*
lrwxr-xr-x 1 root wheel 75 9 Oct 23:42 /usr/bin/python -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7
lrwxr-xr-x 1 root wheel 82 9 Oct 23:42 /usr/bin/python-config -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7-config
lrwxr-xr-x 1 root wheel 75 9 Oct 23:42 /usr/bin/python2 -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7
lrwxr-xr-x 1 root wheel 75 9 Oct 23:42 /usr/bin/python2.7 -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7
lrwxr-xr-x 1 root wheel 82 9 Oct 23:42 /usr/bin/python2.7-config -> ../../System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7-config
-rwxr-xr-x 1 root wheel 31456 5 Dec 04:32 /usr/bin/python3
How can I remove the others python versions except for the original one on the OS X?