How do I replace a Python installed from source with a packaged version?

As Python 3.7 was being prepared I installed Python 3.7.0b3 from source. Now 3.7 is out and I want to use the version packaged for Ubuntu. So I've done

apt-get install python3.7

but

$ which python3.7
/usr/local/bin/python3.7

$ /usr/local/bin/python3.7 --version 
Python 3.7.0b3

How does one uninstall a Python installed from source (on Ubuntu)? Or how can I replace it with the apt repo packaged version?

from How do I replace a Python installed from source with a packaged version?