Uninstall python 3.6

Solution 1:

Warning: This will break Ubuntu 18.04 and 18.10. These instructions apply to the specific situation described in the question, on Ubuntu 16.04.

Warning: I have tested this solution, but not very thoroughly. Make a backup, and proceed with caution.

1. Remove the repo:

   sudo add-apt-repository --remove ppa:fkrull/deadsnakes
   

2. Refresh apt cache:

   sudo apt-get update
   

3. Remove the package:

   sudo apt-get remove --purge python3.6
   

Solution 2:

I followed the instructions above (1:Remove the repo 2:Refresh apt cache 3:Remove the package and found that a lot of my Linux tools and APPS "Disappeared". Not being an expert in identifying and reinstalling each on demand I opted for a full re-install and update. The advise is to make periodic image and backups more like restore points so that you don't have to start from scratch. Make note of your customizations if you are not already documenting the changes to your machine.