accidentally changed Debian-Buster certbot key to Ubuntu key

The title says everything. When I type apt-get update, this error comes E: The repository ‘http://ppa.launchpad.net/certbot/certbot/ubuntu focal Release’ does not have a Release file. N: Updating from such a repository can’t be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. I know what to…