In /etc/syslog-ng/syslog-ng.conf comment out the include part like this:
Then reload syslog-ng
service syslog-ng reload
Note this fix will stop syslog-ng from using all filters in conf.d. This is only a problem if you have custom filters that you wish to use.
In a default OP5 Monitor system there are only this file op5-syslog-ng.conf present in conf.d
ls -l /etc/syslog-ng/conf.d/*
Now you can optionally disable postgres.
chkconfig postgresql off service postgresql stop
You should change in /etc/rsyslog.conf
service rsyslog try-restart
Now you can optionally disable PostgreSQL.
systemctl disable postgresql service postgresql stop
You may also want to disable the daily log rotation to stop error messages from being sent out when it fails, since it will attempt to connect to the database. In the following file:
Comment out the whole line by adding a # to the beginning of the line, and save the file.