First of all, you need to get SSH access. This guide explains how to do it:
Please let me know if you find any issue following this.
Once you access via SSH, you will see something like this:
From that point on, all the command will take place in your Azure instance. So you only need to run these commands:
sudo /opt/bitnami/apps/moodle/bnconfig --disable_banner 1
sudo /opt/bitnami/ctlscript.sh restart apache
I hope it helps