Your Apache is configured by configuration files in /etc/apache2/sites-available. If you used Certbot, there is a “revert” feature to restore web server configurations to their old condition, but this is not done automatically if you delete or uninstall Certbot, perhaps on the same intuition that files downloaded with Firefox or wget should not be automatically deleted if you uninstall those programs.
If you’re looking to remove a Certbot-created redirection, you can probably find it quickly with
grep -r ^Rewrite /etc/apache2
and then editing the resulting file or files to remove the three lines per file that Certbot would have added.