I have recently get hold of a RackSpace Ubuntu server and it has pythons all over the place: 

iPython in 3.5, Pandas in 3.4 &2.7, modules I need like pyodbc etc. are only in 2,7

Therefore, I am keen to clean up the box and, as a 2.7 users, keep everything in 2.7. 

So the key question is, is there a way to remove both 3.4 and 3.5 efficiently at the same time while keeping Python 2.7?
['https://Stackoverflow.com/questions/34198892', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/4779515/']
Removing Python 3 was the worst thing I did since I recently moved to the world of Linux. It removed Firefox, my launcher and, as I read while trying to fix my problem, it may also remove your desktop and terminal! Finally fixed after a long daytime nightmare. Just don't remove Python 3. Keep it there!

If that happens to you, here is the fix:

<https://askubuntu.com/q/384033/402539>

<https://askubuntu.com/q/810854/402539>
neither try any above ways nor `sudo apt autoremove python3` because it will remove all gnome based applications from your system including gnome-terminal. **In case if you have done that mistake and left with kernal only than try`sudo apt install gnome` on kernal.**

try to change your default python version instead removing it. you can do this through **bashrc file** or **export path** command.