I use ZCS 7.2 and I have send all emails through our ISP. Now I would like to change it and send emails directly through my smtp server. Until now I have used authentication done via:
postconf -e smtp_sasl_password_maps=hash:/opt/zimbra/conf/relay_password

Now I would like to remove it to the initial state but I do not know how. Please, can you give me a hint not to upgrade or reinstall the system?