There may be situations when you want to immediately lock an application for all the users; for example, when there are security issues. In that case, you can (temporarily) lock the workspace. Locking a workspace means locking all the user accounts in the workspace. Besides that, the status of all the applications in the workspace will be "unavailable". When the workspace is locked, all the users will not be able to log on to the workspace. Starting an APEX application of a workspace that is locked will result in a message that the application is unavailable.
You need to have access to the APEX internal workspace.