If you need to hide the admin password in OnCall used for publishing your schedule, you can turn off the option that remembers your password.

Start OnCall. Go to File / Preferences and choose the System topic. Turn off the option to Remember admin password.

Each time you run OnCall, you'll need to enter the password to open from the web or publish. It'll remember the password through the session but once you close OnCall and you or someone else restarts, it will ask for the password again.