Use Case
JSD is used in one company as an internal helpdesk center, only. All "customers" are already known and can already log in. From former times, they are also used to send emails for raising issues. By enabling "Email Requests" also the public sign up feature is enabled.
Problem
Some of the customers landing on the portal login page are confused by the link "Sign up for an account" and create a 2nd account. Agents have extra efforts.
Work-a-Round
1) Blocking the sign up page by adding a "Context" element in server.xml or any equivalent on the reverse proxy side. This just works when the customer presses "Submit". Page is not blocked upfront. Following error is then shown: "We are unable to submit your request. Please refresh the page and try again. ...".
2) install SSO, so the customer will (almost) never see the login page.
Solution
Add somewhere (at the customize sidebar?) a checkbox, that simply hides / disables this sign up link with its descriptive text.