If you need to disable an OS user account, you can expire the account using
usermod --expiredate 1. For example, to disable the account for user
sudo usermod --expiredate 1 tom
For more information, please see passwd manual by typing
man passwd and the usermod manual by typing
After disabling a user account, the Administration page will show the disabled user account with a disabled icon in the Status column:
For more information about the Users page, please see the Administration section.