Ubuntu does not start after deleting python3
Python3 is an essential part of your system. Removing Python3 is like removing a wheel from your bicycle.
Yes, you have the power to destroy your system. Use that power carefully. With your great power comes great responsibility. That's how Open Source software works.
- Boot from an Ubuntu LiveUSB (installer) into the "Try Ubuntu" environment.
- Use that environment to back up your data (un-encrypted).
- Then reinstall Ubuntu.
- Then restore your data.