Present in Google's corporate code of conduct since 2000, the "Don't be evil" motto was changed to "Do the right thing" in 2015 for use in Alphabet's code of conduct. However, Google did not drop this slogan until late April/early May, when all references to it have been apparently removed.
https://www.notebookcheck.net/Google-silently-removes-its-Don-t-be-evil-motto-after-almost-two-decades.304468.0.html