If you used our generate_certificate.sh script (you said in this thread that you were using it https://community.bitnami.com/t/ssl-install-on-a-wp-multisite-this-is-the-message-help/64947), you will only need to recover the original bitnami.conf file and restart Apache to use the dummy certificates we include in our solutions again.
sudo mv /opt/bitnami/apache2/conf/bitnami/bitnami.conf /opt/bitnami/apache2/conf/bitnami/bitnami.conf.letsencrypt
sudo mv /opt/bitnami/apache2/conf/bitnami/bitnami.conf.back /opt/bitnami/apache2/conf/bitnami/bitnami.conf
sudo /opt/bitnami/ctlscript.sh restart apache
If you have any issues when modifying the Apache's configuration or restarting it, we have a Support Tool that will gather relevant information for us to analyze your configuration. Could you please download and execute it on the machine where the stack is running by following the steps described in the guide below?
How to Run the Bitnami Support Tool
Please note that you need to paste the code outputted by the tool in your reply.