Close app connections in macOS Server
For security, you can close the Server app’s window when you aren’t actively using it to manage users, groups, or Profile Manager. Leaving a server connection open on an unattended server makes it easier for an unauthorized person to make changes to users, groups, or services. If you select “Remember this password in my keychain,” make sure you log out when you’re away from your server, or require a password for your screen saver in Security & Privacy preferences.
Do any of the following:
Close the Server app’s window.
Choose Manage > Close.
Quit the Server app.