Reset a user’s password in macOS Server
You can use the Server app to reset the passwords of user accounts in your server’s directory domain, but you can’t reset the passwords of imported user accounts.
A user can use System Preferences to change his or her password.
In the Server app sidebar, select Users.
Control-click a user, then choose Change Password.
To reset the passwords of several users, hold down the Command key while selecting users, Control-click a selected user, then choose Change Password.
If you want the user to change the password the next time they log in, select “Require password change at next login.”
Enter the user’s new password in the New Password and Verify fields, then click Change Password.
You can use Password Assistant to help you choose a password. Click the button next to the New Password field to see how secure the password is. The user can change this password in the Users & Groups pane of System Preferences.