How can I remove python 3.6 installed from deadsnakes PPA after upgrade to Ubuntu 18.04?

Solution 1:

After reading the comments below the question I successfully reinstalled python3.6 and want to share with you how I did it.

1. I made a backup of all my data which I would recommend to everyone trying this. Although it worked for me it may fail for some reason on your machine and you don't want to lose your data.
2. I made sure that the deadsnakes PPA is deactivated.

3. I ran the following commands to remove the old version of python3.6 without removing all the dependencies and to directly install the default version.

   sudo dpkg --remove --force-depends python3.6 python3.6-minimal libpython3.6-minimal libpython3.6-stdlib
   sudo apt-get install python3.6 python3.6-minimal libpython3.6-minimal libpython3.6-stdlib
   

4. I ran sudo apt-get update and sudo apt-get upgrade before rebooting my machine.

Maybe this is overcomplicated but it worked for me. Thank you very much for your comments @wjandrea, @Ray, @Zanna.

Solution 2:

For those like me who confirm to delete the 200 packages, I've been able to use a non graphic session (Ctrl+Alt+F1) to reinstall gnome (or cinnamon, I had both installed and both were removed when I remove python3.6).